resources at the end of a research paper

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Dr. Karen Palmer

When using research to support your ideas, creating a list of sources is required. No matter what format you are working with (APA, MLA, etc), you will need to create a list of sources at the end of your paper.

Below is a general overview of some of the most common documentation guidelines for creating a list of sources. You can also find the complete instructions for the most common documentation styles at the websites below:

• APA: http://www.apastyle.org
• MLA: http://www.mla.org
• CMS: http://www.chicagomanualofstyle.org

Some general online searches, especially those conducted on your library databases, are also likely to generate guidelines for a variety of documentation styles. Look for an opportunity to click on a “citation” or “documentation” icon, or ask a member of the library staff for guidance.

You can even get help through the word processing program you typically use. Microsoft Word, for instance, has an entire tab on the taskbar devoted to managing and documenting sources in all three of the styles featured here. Also, don’t forget the free resources that abound on the web from various online writing labs (OWLs) managed by writing programs at colleges and universities across the country.

Citation Machine provides a tool for citing online sources that is particularly helpful.

Developing a List of Sources

Each different documentation style has its own set of guidelines for creating a list of references at the end of the essay (called “works cited” in MLA, “references” in APA, and “bibliography” in CMS).

Source lists should always be in alphabetical order by the first word of each reference, and you should use hanging indentation (with the first line of each reference flush with the margin and subsequent lines indented one-half inch).

• Use the “Insert page” feature to make sure the Works Cited is on its own page at the end of your document. Put your cursor at the end of your paper, then insert a new page. Start typing your list of sources on the new page.
• Center the heading at the top of the page. Follow the guidelines for the documentation style you are using.
• The entire page should be double spaced, just like the rest of your paper.
• Sources should be in alphabetical order.
• Sources should use a Hanging Indent.

Use a Hanging Indent

• Highlight the text you want to format.
• Right click.
• Choose Paragraph.
• Choose Hanging Indent.

1. In your essay rough draft, create a hanging indent.

Additional Resource:

If you don’t know how to cite a certain type of source, please see the OWL at Purdue website: https://owl.purdue.edu/owl/research_and_citation/resources.html 

Attributions

• Overview adapted from “ Chapter 22 ” and licensed under CC BY NC SA .
• Content created by Dr. Karen Palmer and licensed CC BY NC SA .

The RoughWriter's Guide Copyright © 2020 by Dr. Karen Palmer is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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How to Write a Conclusion for Research Papers (with Examples)

The conclusion of a research paper is a crucial section that plays a significant role in the overall impact and effectiveness of your research paper. However, this is also the section that typically receives less attention compared to the introduction and the body of the paper. The conclusion serves to provide a concise summary of the key findings, their significance, their implications, and a sense of closure to the study. Discussing how can the findings be applied in real-world scenarios or inform policy, practice, or decision-making is especially valuable to practitioners and policymakers. The research paper conclusion also provides researchers with clear insights and valuable information for their own work, which they can then build on and contribute to the advancement of knowledge in the field.

The research paper conclusion should explain the significance of your findings within the broader context of your field. It restates how your results contribute to the existing body of knowledge and whether they confirm or challenge existing theories or hypotheses. Also, by identifying unanswered questions or areas requiring further investigation, your awareness of the broader research landscape can be demonstrated.

Remember to tailor the research paper conclusion to the specific needs and interests of your intended audience, which may include researchers, practitioners, policymakers, or a combination of these.

Table of Contents

What is a conclusion in a research paper, summarizing conclusion, editorial conclusion, externalizing conclusion, importance of a good research paper conclusion, how to write a conclusion for your research paper, research paper conclusion examples.

• How to write a research paper conclusion with Paperpal? 

Frequently Asked Questions

A conclusion in a research paper is the final section where you summarize and wrap up your research, presenting the key findings and insights derived from your study. The research paper conclusion is not the place to introduce new information or data that was not discussed in the main body of the paper. When working on how to conclude a research paper, remember to stick to summarizing and interpreting existing content. The research paper conclusion serves the following purposes: 1

• Warn readers of the possible consequences of not attending to the problem.
• Recommend specific course(s) of action.
• Restate key ideas to drive home the ultimate point of your research paper.
• Provide a “take-home” message that you want the readers to remember about your study.

Types of conclusions for research papers

In research papers, the conclusion provides closure to the reader. The type of research paper conclusion you choose depends on the nature of your study, your goals, and your target audience. I provide you with three common types of conclusions:

A summarizing conclusion is the most common type of conclusion in research papers. It involves summarizing the main points, reiterating the research question, and restating the significance of the findings. This common type of research paper conclusion is used across different disciplines.

An editorial conclusion is less common but can be used in research papers that are focused on proposing or advocating for a particular viewpoint or policy. It involves presenting a strong editorial or opinion based on the research findings and offering recommendations or calls to action.

An externalizing conclusion is a type of conclusion that extends the research beyond the scope of the paper by suggesting potential future research directions or discussing the broader implications of the findings. This type of conclusion is often used in more theoretical or exploratory research papers.

Align your conclusion’s tone with the rest of your research paper. Start Writing with Paperpal Now!  

The conclusion in a research paper serves several important purposes:

• Offers Implications and Recommendations : Your research paper conclusion is an excellent place to discuss the broader implications of your research and suggest potential areas for further study. It’s also an opportunity to offer practical recommendations based on your findings.
• Provides Closure : A good research paper conclusion provides a sense of closure to your paper. It should leave the reader with a feeling that they have reached the end of a well-structured and thought-provoking research project.
• Leaves a Lasting Impression : Writing a well-crafted research paper conclusion leaves a lasting impression on your readers. It’s your final opportunity to leave them with a new idea, a call to action, or a memorable quote.

Writing a strong conclusion for your research paper is essential to leave a lasting impression on your readers. Here’s a step-by-step process to help you create and know what to put in the conclusion of a research paper: 2

• Research Statement : Begin your research paper conclusion by restating your research statement. This reminds the reader of the main point you’ve been trying to prove throughout your paper. Keep it concise and clear.
• Key Points : Summarize the main arguments and key points you’ve made in your paper. Avoid introducing new information in the research paper conclusion. Instead, provide a concise overview of what you’ve discussed in the body of your paper.
• Address the Research Questions : If your research paper is based on specific research questions or hypotheses, briefly address whether you’ve answered them or achieved your research goals. Discuss the significance of your findings in this context.
• Significance : Highlight the importance of your research and its relevance in the broader context. Explain why your findings matter and how they contribute to the existing knowledge in your field.
• Implications : Explore the practical or theoretical implications of your research. How might your findings impact future research, policy, or real-world applications? Consider the “so what?” question.
• Future Research : Offer suggestions for future research in your area. What questions or aspects remain unanswered or warrant further investigation? This shows that your work opens the door for future exploration.
• Closing Thought : Conclude your research paper conclusion with a thought-provoking or memorable statement. This can leave a lasting impression on your readers and wrap up your paper effectively. Avoid introducing new information or arguments here.
• Proofread and Revise : Carefully proofread your conclusion for grammar, spelling, and clarity. Ensure that your ideas flow smoothly and that your conclusion is coherent and well-structured.

Write your research paper conclusion 2x faster with Paperpal. Try it now!

Remember that a well-crafted research paper conclusion is a reflection of the strength of your research and your ability to communicate its significance effectively. It should leave a lasting impression on your readers and tie together all the threads of your paper. Now you know how to start the conclusion of a research paper and what elements to include to make it impactful, let’s look at a research paper conclusion sample.

How to write a research paper conclusion with Paperpal?

A research paper conclusion is not just a summary of your study, but a synthesis of the key findings that ties the research together and places it in a broader context. A research paper conclusion should be concise, typically around one paragraph in length. However, some complex topics may require a longer conclusion to ensure the reader is left with a clear understanding of the study’s significance. Paperpal, an AI writing assistant trusted by over 800,000 academics globally, can help you write a well-structured conclusion for your research paper. 

• Sign Up or Log In: Create a new Paperpal account or login with your details.  
• Navigate to Features : Once logged in, head over to the features’ side navigation pane. Click on Templates and you’ll find a suite of generative AI features to help you write better, faster.  
• Generate an outline: Under Templates, select ‘Outlines’. Choose ‘Research article’ as your document type.  
• Select your section: Since you’re focusing on the conclusion, select this section when prompted.  
• Choose your field of study: Identifying your field of study allows Paperpal to provide more targeted suggestions, ensuring the relevance of your conclusion to your specific area of research. 
• Provide a brief description of your study: Enter details about your research topic and findings. This information helps Paperpal generate a tailored outline that aligns with your paper’s content. 
• Generate the conclusion outline: After entering all necessary details, click on ‘generate’. Paperpal will then create a structured outline for your conclusion, to help you start writing and build upon the outline.  
• Write your conclusion: Use the generated outline to build your conclusion. The outline serves as a guide, ensuring you cover all critical aspects of a strong conclusion, from summarizing key findings to highlighting the research’s implications. 
• Refine and enhance: Paperpal’s ‘Make Academic’ feature can be particularly useful in the final stages. Select any paragraph of your conclusion and use this feature to elevate the academic tone, ensuring your writing is aligned to the academic journal standards. 

By following these steps, Paperpal not only simplifies the process of writing a research paper conclusion but also ensures it is impactful, concise, and aligned with academic standards. Sign up with Paperpal today and write your research paper conclusion 2x faster .  

The research paper conclusion is a crucial part of your paper as it provides the final opportunity to leave a strong impression on your readers. In the research paper conclusion, summarize the main points of your research paper by restating your research statement, highlighting the most important findings, addressing the research questions or objectives, explaining the broader context of the study, discussing the significance of your findings, providing recommendations if applicable, and emphasizing the takeaway message. The main purpose of the conclusion is to remind the reader of the main point or argument of your paper and to provide a clear and concise summary of the key findings and their implications. All these elements should feature on your list of what to put in the conclusion of a research paper to create a strong final statement for your work.

A strong conclusion is a critical component of a research paper, as it provides an opportunity to wrap up your arguments, reiterate your main points, and leave a lasting impression on your readers. Here are the key elements of a strong research paper conclusion: 1. Conciseness : A research paper conclusion should be concise and to the point. It should not introduce new information or ideas that were not discussed in the body of the paper. 2. Summarization : The research paper conclusion should be comprehensive enough to give the reader a clear understanding of the research’s main contributions. 3 . Relevance : Ensure that the information included in the research paper conclusion is directly relevant to the research paper’s main topic and objectives; avoid unnecessary details. 4 . Connection to the Introduction : A well-structured research paper conclusion often revisits the key points made in the introduction and shows how the research has addressed the initial questions or objectives. 5. Emphasis : Highlight the significance and implications of your research. Why is your study important? What are the broader implications or applications of your findings? 6 . Call to Action : Include a call to action or a recommendation for future research or action based on your findings.

The length of a research paper conclusion can vary depending on several factors, including the overall length of the paper, the complexity of the research, and the specific journal requirements. While there is no strict rule for the length of a conclusion, but it’s generally advisable to keep it relatively short. A typical research paper conclusion might be around 5-10% of the paper’s total length. For example, if your paper is 10 pages long, the conclusion might be roughly half a page to one page in length.

In general, you do not need to include citations in the research paper conclusion. Citations are typically reserved for the body of the paper to support your arguments and provide evidence for your claims. However, there may be some exceptions to this rule: 1. If you are drawing a direct quote or paraphrasing a specific source in your research paper conclusion, you should include a citation to give proper credit to the original author. 2. If your conclusion refers to or discusses specific research, data, or sources that are crucial to the overall argument, citations can be included to reinforce your conclusion’s validity.

The conclusion of a research paper serves several important purposes: 1. Summarize the Key Points 2. Reinforce the Main Argument 3. Provide Closure 4. Offer Insights or Implications 5. Engage the Reader. 6. Reflect on Limitations

Remember that the primary purpose of the research paper conclusion is to leave a lasting impression on the reader, reinforcing the key points and providing closure to your research. It’s often the last part of the paper that the reader will see, so it should be strong and well-crafted.

• Makar, G., Foltz, C., Lendner, M., & Vaccaro, A. R. (2018). How to write effective discussion and conclusion sections. Clinical spine surgery, 31(8), 345-346.
• Bunton, D. (2005). The structure of PhD conclusion chapters.  Journal of English for academic purposes ,  4 (3), 207-224.

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How to write a strong conclusion for your research paper

Last updated

17 February 2024

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Writing a research paper is a chance to share your knowledge and hypothesis. It's an opportunity to demonstrate your many hours of research and prove your ability to write convincingly.

Ideally, by the end of your research paper, you'll have brought your readers on a journey to reach the conclusions you've pre-determined. However, if you don't stick the landing with a good conclusion, you'll risk losing your reader’s trust.

Writing a strong conclusion for your research paper involves a few important steps, including restating the thesis and summing up everything properly.

Find out what to include and what to avoid, so you can effectively demonstrate your understanding of the topic and prove your expertise.

• Why is a good conclusion important?

A good conclusion can cement your paper in the reader’s mind. Making a strong impression in your introduction can draw your readers in, but it's the conclusion that will inspire them.

• What to include in a research paper conclusion

There are a few specifics you should include in your research paper conclusion. Offer your readers some sense of urgency or consequence by pointing out why they should care about the topic you have covered. Discuss any common problems associated with your topic and provide suggestions as to how these problems can be solved or addressed.

The conclusion should include a restatement of your initial thesis. Thesis statements are strengthened after you’ve presented supporting evidence (as you will have done in the paper), so make a point to reintroduce it at the end.

Finally, recap the main points of your research paper, highlighting the key takeaways you want readers to remember. If you've made multiple points throughout the paper, refer to the ones with the strongest supporting evidence.

• Steps for writing a research paper conclusion

Many writers find the conclusion the most challenging part of any research project . By following these three steps, you'll be prepared to write a conclusion that is effective and concise.

• Step 1: Restate the problem

Always begin by restating the research problem in the conclusion of a research paper. This serves to remind the reader of your hypothesis and refresh them on the main point of the paper. 

When restating the problem, take care to avoid using exactly the same words you employed earlier in the paper.

• Step 2: Sum up the paper

After you've restated the problem, sum up the paper by revealing your overall findings. The method for this differs slightly, depending on whether you're crafting an argumentative paper or an empirical paper.

Argumentative paper: Restate your thesis and arguments

Argumentative papers involve introducing a thesis statement early on. In crafting the conclusion for an argumentative paper, always restate the thesis, outlining the way you've developed it throughout the entire paper.

It might be appropriate to mention any counterarguments in the conclusion, so you can demonstrate how your thesis is correct or how the data best supports your main points.

Empirical paper: Summarize research findings

Empirical papers break down a series of research questions. In your conclusion, discuss the findings your research revealed, including any information that surprised you.

Be clear about the conclusions you reached, and explain whether or not you expected to arrive at these particular ones.

• Step 3: Discuss the implications of your research

Argumentative papers and empirical papers also differ in this part of a research paper conclusion. Here are some tips on crafting conclusions for argumentative and empirical papers.

Argumentative paper: Powerful closing statement

In an argumentative paper, you'll have spent a great deal of time expressing the opinions you formed after doing a significant amount of research. Make a strong closing statement in your argumentative paper's conclusion to share the significance of your work.

You can outline the next steps through a bold call to action, or restate how powerful your ideas turned out to be.

Empirical paper: Directions for future research

Empirical papers are broader in scope. They usually cover a variety of aspects and can include several points of view.

To write a good conclusion for an empirical paper, suggest the type of research that could be done in the future, including methods for further investigation or outlining ways other researchers might proceed.

If you feel your research had any limitations, even if they were outside your control, you could mention these in your conclusion.

After you finish outlining your conclusion, ask someone to read it and offer feedback. In any research project you're especially close to, it can be hard to identify problem areas. Having a close friend or someone whose opinion you value read the research paper and provide honest feedback can be invaluable. Take note of any suggested edits and consider incorporating them into your paper if they make sense.

• Things to avoid in a research paper conclusion

Keep these aspects to avoid in mind as you're writing your conclusion and refer to them after you've created an outline.

Dry summary

Writing a memorable, succinct conclusion is arguably more important than a strong introduction. Take care to avoid just rephrasing your main points, and don't fall into the trap of repeating dry facts or citations.

You can provide a new perspective for your readers to think about or contextualize your research. Either way, make the conclusion vibrant and interesting, rather than a rote recitation of your research paper’s highlights.

Clichéd or generic phrasing

Your research paper conclusion should feel fresh and inspiring. Avoid generic phrases like "to sum up" or "in conclusion." These phrases tend to be overused, especially in an academic context and might turn your readers off.

The conclusion also isn't the time to introduce colloquial phrases or informal language. Retain a professional, confident tone consistent throughout your paper’s conclusion so it feels exciting and bold.

New data or evidence

While you should present strong data throughout your paper, the conclusion isn't the place to introduce new evidence. This is because readers are engaged in actively learning as they read through the body of your paper.

By the time they reach the conclusion, they will have formed an opinion one way or the other (hopefully in your favor!). Introducing new evidence in the conclusion will only serve to surprise or frustrate your reader.

Ignoring contradictory evidence

If your research reveals contradictory evidence, don't ignore it in the conclusion. This will damage your credibility as an expert and might even serve to highlight the contradictions.

Be as transparent as possible and admit to any shortcomings in your research, but don't dwell on them for too long.

Ambiguous or unclear resolutions

The point of a research paper conclusion is to provide closure and bring all your ideas together. You should wrap up any arguments you introduced in the paper and tie up any loose ends, while demonstrating why your research and data are strong.

Use direct language in your conclusion and avoid ambiguity. Even if some of the data and sources you cite are inconclusive or contradictory, note this in your conclusion to come across as confident and trustworthy.

• Examples of research paper conclusions

Your research paper should provide a compelling close to the paper as a whole, highlighting your research and hard work. While the conclusion should represent your unique style, these examples offer a starting point:

Ultimately, the data we examined all point to the same conclusion: Encouraging a good work-life balance improves employee productivity and benefits the company overall. The research suggests that when employees feel their personal lives are valued and respected by their employers, they are more likely to be productive when at work. In addition, company turnover tends to be reduced when employees have a balance between their personal and professional lives. While additional research is required to establish ways companies can support employees in creating a stronger work-life balance, it's clear the need is there.

Social media is a primary method of communication among young people. As we've seen in the data presented, most young people in high school use a variety of social media applications at least every hour, including Instagram and Facebook. While social media is an avenue for connection with peers, research increasingly suggests that social media use correlates with body image issues. Young girls with lower self-esteem tend to use social media more often than those who don't log onto social media apps every day. As new applications continue to gain popularity, and as more high school students are given smartphones, more research will be required to measure the effects of prolonged social media use.

What are the different kinds of research paper conclusions?

There are no formal types of research paper conclusions. Ultimately, the conclusion depends on the outline of your paper and the type of research you’re presenting. While some experts note that research papers can end with a new perspective or commentary, most papers should conclude with a combination of both. The most important aspect of a good research paper conclusion is that it accurately represents the body of the paper.

Can I present new arguments in my research paper conclusion?

Research paper conclusions are not the place to introduce new data or arguments. The body of your paper is where you should share research and insights, where the reader is actively absorbing the content. By the time a reader reaches the conclusion of the research paper, they should have formed their opinion. Introducing new arguments in the conclusion can take a reader by surprise, and not in a positive way. It might also serve to frustrate readers.

How long should a research paper conclusion be?

There's no set length for a research paper conclusion. However, it's a good idea not to run on too long, since conclusions are supposed to be succinct. A good rule of thumb is to keep your conclusion around 5 to 10 percent of the paper's total length. If your paper is 10 pages, try to keep your conclusion under one page.

What should I include in a research paper conclusion?

A good research paper conclusion should always include a sense of urgency, so the reader can see how and why the topic should matter to them. You can also note some recommended actions to help fix the problem and some obstacles they might encounter. A conclusion should also remind the reader of the thesis statement, along with the main points you covered in the paper. At the end of the conclusion, add a powerful closing statement that helps cement the paper in the mind of the reader.

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Writing a Research Paper

This page lists some of the stages involved in writing a library-based research paper.

Although this list suggests that there is a simple, linear process to writing such a paper, the actual process of writing a research paper is often a messy and recursive one, so please use this outline as a flexible guide.

Discovering, Narrowing, and Focusing a Researchable Topic

• Try to find a topic that truly interests you
• Try writing your way to a topic
• Talk with your course instructor and classmates about your topic
• Pose your topic as a question to be answered or a problem to be solved

Finding, Selecting, and Reading Sources

You will need to look at the following types of sources:

• library catalog, periodical indexes, bibliographies, suggestions from your instructor
• primary vs. secondary sources
• journals, books, other documents

Grouping, Sequencing, and Documenting Information

The following systems will help keep you organized:

• a system for noting sources on bibliography cards
• a system for organizing material according to its relative importance
• a system for taking notes

Writing an Outline and a Prospectus for Yourself

Consider the following questions:

• What is the topic?
• Why is it significant?
• What background material is relevant?
• What is my thesis or purpose statement?
• What organizational plan will best support my purpose?

Writing the Introduction

In the introduction you will need to do the following things:

• present relevant background or contextual material
• define terms or concepts when necessary
• explain the focus of the paper and your specific purpose
• reveal your plan of organization

Writing the Body

• Use your outline and prospectus as flexible guides
• Build your essay around points you want to make (i.e., don’t let your sources organize your paper)
• Integrate your sources into your discussion
• Summarize, analyze, explain, and evaluate published work rather than merely reporting it
• Move up and down the “ladder of abstraction” from generalization to varying levels of detail back to generalization

Writing the Conclusion

• If the argument or point of your paper is complex, you may need to summarize the argument for your reader.
• If prior to your conclusion you have not yet explained the significance of your findings or if you are proceeding inductively, use the end of your paper to add your points up, to explain their significance.
• Move from a detailed to a general level of consideration that returns the topic to the context provided by the introduction.
• Perhaps suggest what about this topic needs further research.

Revising the Final Draft

• Check overall organization : logical flow of introduction, coherence and depth of discussion in body, effectiveness of conclusion.
• Paragraph level concerns : topic sentences, sequence of ideas within paragraphs, use of details to support generalizations, summary sentences where necessary, use of transitions within and between paragraphs.
• Sentence level concerns: sentence structure, word choices, punctuation, spelling.
• Documentation: consistent use of one system, citation of all material not considered common knowledge, appropriate use of endnotes or footnotes, accuracy of list of works cited.

Academic and Professional Writing

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How to Write a Research Paper: Parts of the Paper

• Choosing Your Topic
• Citation & Style Guides This link opens in a new window
• Critical Thinking
• Evaluating Information
• Parts of the Paper
• Writing Tips from UNC-Chapel Hill
• Librarian Contact

Parts of the Research Paper Papers should have a beginning, a middle, and an end. Your introductory paragraph should grab the reader's attention, state your main idea, and indicate how you will support it. The body of the paper should expand on what you have stated in the introduction. Finally, the conclusion restates the paper's thesis and should explain what you have learned, giving a wrap up of your main ideas.

1. The Title The title should be specific and indicate the theme of the research and what ideas it addresses. Use keywords that help explain your paper's topic to the reader. Try to avoid abbreviations and jargon. Think about keywords that people would use to search for your paper and include them in your title.

2. The Abstract The abstract is used by readers to get a quick overview of your paper. Typically, they are about 200 words in length (120 words minimum to  250 words maximum). The abstract should introduce the topic and thesis, and should provide a general statement about what you have found in your research. The abstract allows you to mention each major aspect of your topic and helps readers decide whether they want to read the rest of the paper. Because it is a summary of the entire research paper, it is often written last. 

3. The Introduction The introduction should be designed to attract the reader's attention and explain the focus of the research. You will introduce your overview of the topic,  your main points of information, and why this subject is important. You can introduce the current understanding and background information about the topic. Toward the end of the introduction, you add your thesis statement, and explain how you will provide information to support your research questions. This provides the purpose and focus for the rest of the paper.

4. Thesis Statement Most papers will have a thesis statement or main idea and supporting facts/ideas/arguments. State your main idea (something of interest or something to be proven or argued for or against) as your thesis statement, and then provide your supporting facts and arguments. A thesis statement is a declarative sentence that asserts the position a paper will be taking. It also points toward the paper's development. This statement should be both specific and arguable. Generally, the thesis statement will be placed at the end of the first paragraph of your paper. The remainder of your paper will support this thesis.

Students often learn to write a thesis as a first step in the writing process, but often, after research, a writer's viewpoint may change. Therefore a thesis statement may be one of the final steps in writing. 

Examples of Thesis Statements from Purdue OWL

5. The Literature Review The purpose of the literature review is to describe past important research and how it specifically relates to the research thesis. It should be a synthesis of the previous literature and the new idea being researched. The review should examine the major theories related to the topic to date and their contributors. It should include all relevant findings from credible sources, such as academic books and peer-reviewed journal articles. You will want  to:

• Explain how the literature helps the researcher understand the topic.
• Try to show connections and any disparities between the literature.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.

More about writing a literature review. . .

6. The Discussion ​The purpose of the discussion is to interpret and describe what you have learned from your research. Make the reader understand why your topic is important. The discussion should always demonstrate what you have learned from your readings (and viewings) and how that learning has made the topic evolve, especially from the short description of main points in the introduction.Explain any new understanding or insights you have had after reading your articles and/or books. Paragraphs should use transitioning sentences to develop how one paragraph idea leads to the next. The discussion will always connect to the introduction, your thesis statement, and the literature you reviewed, but it does not simply repeat or rearrange the introduction. You want to: 

• Demonstrate critical thinking, not just reporting back facts that you gathered.
• If possible, tell how the topic has evolved over the past and give it's implications for the future.
• Fully explain your main ideas with supporting information.
• Explain why your thesis is correct giving arguments to counter points.

7. The Conclusion A concluding paragraph is a brief summary of your main ideas and restates the paper's main thesis, giving the reader the sense that the stated goal of the paper has been accomplished. What have you learned by doing this research that you didn't know before? What conclusions have you drawn? You may also want to suggest further areas of study, improvement of research possibilities, etc. to demonstrate your critical thinking regarding your research.

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Online Guide to Writing and Research

Academic integrity and documentation, explore more of umgc.

• Online Guide to Writing

Types of Documentation

Bibliographies and Source Lists

What is a bibliography.

A bibliography is a list of books and other source material that you have used in preparing a research paper. Sometimes these lists will include works that you consulted but did not cite specifically in your assignment. Consult the style guide required for your assignment to determine the specific title of your bibliography page as well as how to cite each source type. Bibliographies are usually placed at the end of your research paper.

What is an annotated bibliography?

A special kind of bibliography, the annotated bibliography, is often used to direct your readers to other books and resources on your topic. An instructor may ask you to prepare an annotated bibliography to help you narrow down a topic for your research assignment. Such bibliographies offer a few lines of information, typically 150-300 words, summarizing the content of the resource after the bibliographic entry.   

Example of Annotated Bibliographic Entry in MLA Style

Waddell, Marie L., Robert M. Esch, and Roberta R. Walker. The Art of Styling         Sentences: 20 Patterns for Success. 3rd ed. New York: Barron’s, 1993.         A comprehensive look at 20 sentence patterns and their variations to         teach students how to write effective sentences by imitating good style.

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Table of Contents: Online Guide to Writing

Chapter 1: College Writing

How Does College Writing Differ from Workplace Writing?

What Is College Writing?

Why So Much Emphasis on Writing?

Chapter 2: The Writing Process

Doing Exploratory Research

Getting from Notes to Your Draft

Introduction

Prewriting - Techniques to Get Started - Mining Your Intuition

Prewriting: Targeting Your Audience

Prewriting: Techniques to Get Started

Prewriting: Understanding Your Assignment

Rewriting: Being Your Own Critic

Rewriting: Creating a Revision Strategy

Rewriting: Getting Feedback

Rewriting: The Final Draft

Techniques to Get Started - Outlining

Techniques to Get Started - Using Systematic Techniques

Thesis Statement and Controlling Idea

Writing: Getting from Notes to Your Draft - Freewriting

Writing: Getting from Notes to Your Draft - Summarizing Your Ideas

Writing: Outlining What You Will Write

Chapter 3: Thinking Strategies

A Word About Style, Voice, and Tone

A Word About Style, Voice, and Tone: Style Through Vocabulary and Diction

Critical Strategies and Writing

Critical Strategies and Writing: Analysis

Critical Strategies and Writing: Evaluation

Critical Strategies and Writing: Persuasion

Critical Strategies and Writing: Synthesis

Developing a Paper Using Strategies

Kinds of Assignments You Will Write

Patterns for Presenting Information

Patterns for Presenting Information: Critiques

Patterns for Presenting Information: Discussing Raw Data

Patterns for Presenting Information: General-to-Specific Pattern

Patterns for Presenting Information: Problem-Cause-Solution Pattern

Patterns for Presenting Information: Specific-to-General Pattern

Patterns for Presenting Information: Summaries and Abstracts

Supporting with Research and Examples

Writing Essay Examinations

Writing Essay Examinations: Make Your Answer Relevant and Complete

Writing Essay Examinations: Organize Thinking Before Writing

Writing Essay Examinations: Read and Understand the Question

Chapter 4: The Research Process

Planning and Writing a Research Paper

Planning and Writing a Research Paper: Ask a Research Question

Planning and Writing a Research Paper: Cite Sources

Planning and Writing a Research Paper: Collect Evidence

Planning and Writing a Research Paper: Decide Your Point of View, or Role, for Your Research

Planning and Writing a Research Paper: Draw Conclusions

Planning and Writing a Research Paper: Find a Topic and Get an Overview

Planning and Writing a Research Paper: Manage Your Resources

Planning and Writing a Research Paper: Outline

Planning and Writing a Research Paper: Survey the Literature

Planning and Writing a Research Paper: Work Your Sources into Your Research Writing

Research Resources: Where Are Research Resources Found? - Human Resources

Research Resources: What Are Research Resources?

Research Resources: Where Are Research Resources Found?

Research Resources: Where Are Research Resources Found? - Electronic Resources

Research Resources: Where Are Research Resources Found? - Print Resources

Structuring the Research Paper: Formal Research Structure

Structuring the Research Paper: Informal Research Structure

The Nature of Research

The Research Assignment: How Should Research Sources Be Evaluated?

The Research Assignment: When Is Research Needed?

The Research Assignment: Why Perform Research?

Chapter 5: Academic Integrity

Academic Integrity

Giving Credit to Sources

Giving Credit to Sources: Copyright Laws

Giving Credit to Sources: Documentation

Giving Credit to Sources: Style Guides

Integrating Sources

Practicing Academic Integrity

Practicing Academic Integrity: Keeping Accurate Records

Practicing Academic Integrity: Managing Source Material

Practicing Academic Integrity: Managing Source Material - Paraphrasing Your Source

Practicing Academic Integrity: Managing Source Material - Quoting Your Source

Practicing Academic Integrity: Managing Source Material - Summarizing Your Sources

Types of Documentation: Bibliographies and Source Lists

Types of Documentation: Citing World Wide Web Sources

Types of Documentation: In-Text or Parenthetical Citations

Types of Documentation: In-Text or Parenthetical Citations - APA Style

Types of Documentation: In-Text or Parenthetical Citations - CSE/CBE Style

Types of Documentation: In-Text or Parenthetical Citations - Chicago Style

Types of Documentation: In-Text or Parenthetical Citations - MLA Style

Types of Documentation: Note Citations

Chapter 6: Using Library Resources

Finding Library Resources

Chapter 7: Assessing Your Writing

How Is Writing Graded?

How Is Writing Graded?: A General Assessment Tool

The Draft Stage

The Draft Stage: The First Draft

The Draft Stage: The Revision Process and the Final Draft

The Draft Stage: Using Feedback

The Research Stage

Using Assessment to Improve Your Writing

Chapter 8: Other Frequently Assigned Papers

Reviews and Reaction Papers: Article and Book Reviews

Reviews and Reaction Papers: Reaction Papers

Writing Arguments

Writing Arguments: Adapting the Argument Structure

Writing Arguments: Purposes of Argument

Writing Arguments: References to Consult for Writing Arguments

Writing Arguments: Steps to Writing an Argument - Anticipate Active Opposition

Writing Arguments: Steps to Writing an Argument - Determine Your Organization

Writing Arguments: Steps to Writing an Argument - Develop Your Argument

Writing Arguments: Steps to Writing an Argument - Introduce Your Argument

Writing Arguments: Steps to Writing an Argument - State Your Thesis or Proposition

Writing Arguments: Steps to Writing an Argument - Write Your Conclusion

Writing Arguments: Types of Argument

Appendix A: Books to Help Improve Your Writing

Dictionaries

General Style Manuals

Researching on the Internet

Special Style Manuals

Writing Handbooks

Appendix B: Collaborative Writing and Peer Reviewing

Collaborative Writing: Assignments to Accompany the Group Project

Collaborative Writing: Informal Progress Report

Collaborative Writing: Issues to Resolve

Collaborative Writing: Methodology

Collaborative Writing: Peer Evaluation

Collaborative Writing: Tasks of Collaborative Writing Group Members

Collaborative Writing: Writing Plan

General Introduction

Peer Reviewing

Appendix C: Developing an Improvement Plan

Working with Your Instructor’s Comments and Grades

Appendix D: Writing Plan and Project Schedule

Devising a Writing Project Plan and Schedule

Reviewing Your Plan with Others

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How to Write a Bibliography for a Research Paper

Do not try to “wow” your instructor with a long bibliography when your instructor requests only a works cited page. It is tempting, after doing a lot of work to research a paper, to try to include summaries on each source as you write your paper so that your instructor appreciates how much work you did. That is a trap you want to avoid. MLA style, the one that is most commonly followed in high schools and university writing courses, dictates that you include only the works you actually cited in your paper—not all those that you used.

Academic Writing, Editing, Proofreading, And Problem Solving Services

Get 10% off with 24start discount code, assembling bibliographies and works cited.

• If your assignment calls for a bibliography, list all the sources you consulted in your research.
• If your assignment calls for a works cited or references page, include only the sources you quote, summarize, paraphrase, or mention in your paper.
• If your works cited page includes a source that you did not cite in your paper, delete it.
• All in-text citations that you used at the end of quotations, summaries, and paraphrases to credit others for their ideas,words, and work must be accompanied by a cited reference in the bibliography or works cited. These references must include specific information about the source so that your readers can identify precisely where the information came from.The citation entries on a works cited page typically include the author’s name, the name of the article, the name of the publication, the name of the publisher (for books), where it was published (for books), and when it was published.

The good news is that you do not have to memorize all the many ways the works cited entries should be written. Numerous helpful style guides are available to show you the information that should be included, in what order it should appear, and how to format it. The format often differs according to the style guide you are using. The Modern Language Association (MLA) follows a particular style that is a bit different from APA (American Psychological Association) style, and both are somewhat different from the Chicago Manual of Style (CMS). Always ask your teacher which style you should use.

A bibliography usually appears at the end of a paper on its own separate page. All bibliography entries—books, periodicals, Web sites, and nontext sources such radio broadcasts—are listed together in alphabetical order. Books and articles are alphabetized by the author’s last name.

Most teachers suggest that you follow a standard style for listing different types of sources. If your teacher asks you to use a different form, however, follow his or her instructions. Take pride in your bibliography. It represents some of the most important work you’ve done for your research paper—and using proper form shows that you are a serious and careful researcher.

Bibliography Entry for a Book

A bibliography entry for a book begins with the author’s name, which is written in this order: last name, comma, first name, period. After the author’s name comes the title of the book. If you are handwriting your bibliography, underline each title. If you are working on a computer, put the book title in italicized type. Be sure to capitalize the words in the title correctly, exactly as they are written in the book itself. Following the title is the city where the book was published, followed by a colon, the name of the publisher, a comma, the date published, and a period. Here is an example:

Format : Author’s last name, first name. Book Title. Place of publication: publisher, date of publication.

• A book with one author : Hartz, Paula.  Abortion: A Doctor’s Perspective, a Woman’s Dilemma . New York: Donald I. Fine, Inc., 1992.
• A book with two or more authors : Landis, Jean M. and Rita J. Simon.  Intelligence: Nature or Nurture?  New York: HarperCollins, 1998.

Bibliography Entry for a Periodical

A bibliography entry for a periodical differs slightly in form from a bibliography entry for a book. For a magazine article, start with the author’s last name first, followed by a comma, then the first name and a period. Next, write the title of the article in quotation marks, and include a period (or other closing punctuation) inside the closing quotation mark. The title of the magazine is next, underlined or in italic type, depending on whether you are handwriting or using a computer, followed by a period. The date and year, followed by a colon and the pages on which the article appeared, come last. Here is an example:

Format:  Author’s last name, first name. “Title of the Article.” Magazine. Month and year of publication: page numbers.

• Article in a monthly magazine : Crowley, J.E.,T.E. Levitan and R.P. Quinn.“Seven Deadly Half-Truths About Women.”  Psychology Today  March 1978: 94–106.
• Article in a weekly magazine : Schwartz, Felice N.“Management,Women, and the New Facts of Life.”  Newsweek  20 July 2006: 21–22.
• Signed newspaper article : Ferraro, Susan. “In-law and Order: Finding Relative Calm.”  The Daily News  30 June 1998: 73.
• Unsigned newspaper article : “Beanie Babies May Be a Rotten Nest Egg.”  Chicago Tribune  21 June 2004: 12.

Bibliography Entry for a Web Site

For sources such as Web sites include the information a reader needs to find the source or to know where and when you found it. Always begin with the last name of the author, broadcaster, person you interviewed, and so on. Here is an example of a bibliography for a Web site:

Format : Author.“Document Title.” Publication or Web site title. Date of publication. Date of access.

Example : Dodman, Dr. Nicholas. “Dog-Human Communication.”  Pet Place . 10 November 2006.  23 January 2014 < http://www.petplace.com/dogs/dog-human-communication-2/page1.aspx >

After completing the bibliography you can breathe a huge sigh of relief and pat yourself on the back. You probably plan to turn in your work in printed or handwritten form, but you also may be making an oral presentation. However you plan to present your paper, do your best to show it in its best light. You’ve put a great deal of work and thought into this assignment, so you want your paper to look and sound its best. You’ve completed your research paper!

Back to  How To Write A Research Paper .

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In-Text Citations

Resources on using in-text citations in APA style

Reference List

Resources on writing an APA style reference list, including citation formats

Other APA Resources

• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 11. Citing Sources
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

A citation is a formal reference to a published or unpublished source that you consulted and obtained information from while writing your research paper. It refers to a source of information that supports a factual statement, proposition, argument, or assertion or any quoted text obtained from a book, article, web site, or any other type of material . In-text citations are embedded within the body of your paper and use a shorthand notation style that refers to a complete description of the item at the end of the paper. Materials cited at the end of a paper may be listed under the heading References, Sources, Works Cited, or Bibliography. Rules on how to properly cite a source depends on the writing style manual your professor wants you to use for the class [e.g., APA, MLA, Chicago, Turabian, etc.]. Note that some disciplines have their own citation rules [e.g., law].

Citations: Overview. OASIS Writing Center, Walden University; Research and Citation. The Writing Lab and The OWL. Purdue University; Citing Sources. University Writing Center, Texas A&M University.

Citing Your Sources

Reasons for Citing Sources in Your Research Paper

English scientist, Sir Isaac Newton, once wrote, "If I have seen further, it is by standing on the shoulders of giants.”* Citations support learning how to "see further" through processes of intellectual discovery, critical thinking, and applying a deliberate method of navigating through the scholarly landscape by tracking how cited works are propagated by scholars over time and the subsequent ways this leads to the devarication of new knowledge.

Listed below are specific reasons why citing sources is an important part of doing good research.

• Shows the reader where to find more information . Citations help readers expand their understanding and knowledge about the issues being investigated. One of the most effective strategies for locating authoritative, relevant sources about a research problem is to review materials cited in studies published by other authors. In this way, the sources you cite help the reader identify where to go to examine the topic in more depth and detail.
• Increases your credibility as an author . Citations to the words, ideas, and arguments of scholars demonstrates that you have conducted a thorough review of the literature and, therefore, you are reporting your research results or proposing recommended courses of action from an informed and critically engaged perspective. Your citations offer evidence that you effectively contemplated, evaluated, and synthesized sources of information in relation to your conceptualization of the research problem.
• Illustrates the non-linear and contested nature of knowledge creation . The sources you cite show the reader how you characterized the dynamics of prior knowledge creation relevant to the research problem and how you managed to identify the contested relationships between problems and solutions proposed among scholars. Citations don't just list materials used in your study, they tell a story about how prior knowledge-making emerged from a constant state of creation, renewal, and transformation.
• Reinforces your arguments . Sources cited in your paper provide the evidence that readers need to determine that you properly addressed the “So What?” question. This refers to whether you considered the relevance and significance of the research problem, its implications applied to creating new knowledge, and its importance for improving practice. In this way, citations draw attention to and support the legitimacy and originality of your own ideas and assertions.
• Demonstrates that you "listened" to relevant conversations among scholars before joining in . Your citations tell the reader where you developed an understanding of the debates among scholars. They show how you educated yourself about ongoing conversations taking place within relevant communities of researchers before inserting your own ideas and arguments. In peer-reviewed scholarship, most of these conversations emerge within books, research reports, journal articles, and other cited works.
• Delineates alternative approaches to explaining the research problem . If you disagree with prior research assumptions or you believe that a topic has been understudied or you find that there is a gap in how scholars have understood a problem, your citations serve as the source materials from which to analyze and present an alternative viewpoint or to assert that a different course of action should be pursued. In short, the materials you cite serve as the means by which to argue persuasively against long-standing assumptions promulgated in prior studies.
• Helps the reader understand contextual aspects of your research . Cited sources help readers understand the specific circumstances, conditions, and settings of the problem being investigated and, by extension, how your arguments can be fully understood and assessed. Citations place your line of reasoning within a specific contextualized framework based on how others have studied the problem and how you interpreted their findings in support of your overall research objectives.
• Frames the development of concepts and ideas within the literature . No topic in the social and behavioral sciences rests in isolation from research that has taken place in the past. Your citations help the reader understand the growth and transformation of the theoretical assumptions, key concepts, and systematic inquiries that emerged prior to your engagement with the research problem.
• Underscores sources that were most important to you . Your citations represent a set of choices made about what you determined to be the most important sources for understanding the topic. They not only list what you discovered, but why it matters and how the materials you chose to cite fit within the broader context of your research design and arguments. As part of an overall assessment of the study’s validity and reliability , the choices you make also helps the reader determine what sources of research may have been excluded.
• Provides evidence of interdisciplinary thinking . An important principle of good research is to extend your review of the literature beyond the predominant disciplinary space where scholars have previously examined a topic. Citations provide evidence that you have integrated epistemological arguments, observations, and/or methodological strategies of other disciplines into your paper, thereby demonstrating that you understand the complex, interconnected nature of contemporary research topics.
• Forms the basis for bibliometric analysis of research . Bibliometric analysis is a quantitative method used, for example, to identify and predict emerging trends in research, document patterns of collaboration among scholars, explore the intellectual structure of a specific domain of research, map the development of research within and across disciplines, or identify gaps in knowledge within the literature. Bibliometrics data can also be used to visually map relationships among published studies. An author's citations to books, journal articles, research reports, and other publications represent the raw data used in bibliometric research.
• Supports critical thinking and independent learning . Evaluating the authenticity, reliability, validity, and originality of prior research is an act of interpretation and introspective reasoning applied to assessing whether a source of information will contribute to understanding the problem in ways that are persuasive and align with your overall research objectives. Reviewing and citing prior studies represents a deliberate act of critically scrutinizing each source as part of your overall assessment of how scholars have confronted the research problem.
• Honors the achievements of others . As Susan Blum recently noted,** citations not only identify sources used, they acknowledge the achievements of scholars within the larger network of research about the topic. Citing sources is a normative act of professionalism within academe and a way to highlight and recognize the work of scholars who likely do not obtain any tangible benefits or monetary value from their research endeavors. Your citations help to validate the work of others.

*Vernon. Jamie L. "On the Shoulder of Giants." American Scientist 105 (July-August 2017): 194.

**Blum, Susan D. "In Defense of the Morality of Citation.” Inside Higher Ed , January 29, 2024.

Aksnes, Dag W., Liv Langfeldt, and Paul Wouters. "Citations, Citation Indicators, and Research Quality: An Overview of Basic Concepts and Theories." Sage Open 9 (January-March 2019): https://doi.org/10.1177/2158244019829575; Blum, Susan Debra. My Word!: Plagiarism and College Culture . Ithaca, NY: Cornell University Press, 2009; Bretag, Tracey., editor. Handbook of Academic Integrity . Singapore: Springer Singapore, 2020; Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers . 7th edition. Boston, MA: Pearson, 2012; D'Angelo, Barbara J. "Using Source Analysis to Promote Critical Thinking." Research Strategies 18 (Winter 2001): 303-309; Donthu, Naveen et al. “How to Conduct a Bibliometric Analysis: An Overview and Guidelines.” Journal of Business Research 133 (2021): 285-296; Mauer, Barry and John Venecek. “Scholarship as Conversation.” Strategies for Conducting Literary Research, University of Central Florida, 2021; Öztürk, Oguzhan, Ridvan Kocaman, and Dominik K. Kanbach. "How to Design Bibliometric Research: An Overview and a Framework Proposal." Review of Managerial Science (2024): 1-29; Why Cite? Poorvu Center for Teaching and Learning, Yale University; Citing Information. The Writing Center. University of North Carolina; Harvard Guide to Using Sources. Harvard College Writing Program. Harvard University; Newton, Philip. "Academic Integrity: A Quantitative Study of Confidence and Understanding in Students at the Start of Their Higher Education."  Assessment and Evaluation in Higher Education 41 (2016): 482-497; Referencing More Effectively. Academic Skills Centre. University of Canberra; Using Sources. Yale College Writing Center. Yale University; Vosburgh, Richard M. "Closing the Academic-practitioner Gap: Research Must Answer the “SO WHAT” Question." H uman Resource Management Review 32 (March 2022): 100633; When and Why to Cite Sources. Information Literacy Playlists, SUNY, Albany Libraries.

Structure and Writing Style

Referencing your sources means systematically showing what information or ideas you acquired from another author’s work, and identifying where that information come from . You must cite research in order to do research, but at the same time, you must delineate what are your original thoughts and ideas and what are the thoughts and ideas of others. Citations help achieve this. Procedures used to cite sources vary among different fields of study. If not outlined in your course syllabus or writing assignment, always speak with your professor about what writing style for citing sources should be used for the class because it is important to fully understand the citation style to be used in your paper, and to apply it consistently. If your professor defers and tells you to "choose whatever you want, just be consistent," then choose the citation style you are most familiar with or that is appropriate to your major [e.g., use Chicago style if you are majoring in history; use APA if its an education course; use MLA if it is literature or a general writing course].

GENERAL GUIDELINES

1. Are there any reasons I should avoid referencing other people's work? No. If placed in the proper context, r eferencing other people's research is never an indication that your work is substandard or lacks originality. In fact, the opposite is true. If you write your paper without adequate references to previous studies, you are signaling to the reader that you are not familiar with the literature on the topic, thereby, undermining the validity of your study and your credibility as a researcher. Including references in academic writing is one of the most important ways to demonstrate your knowledge and understanding of how the research problem has been addressed. It is the intellectual packaging around which you present your thoughts, ideas, and arguments to the reader.

2. What should I do if I find out that my great idea has already been studied by another researcher? It can be frustrating to come up with what you believe is a great topic only to find that it's already been thoroughly studied. However, do not become frustrated by this. You can acknowledge the prior research by writing in the text of your paper [see also Smith, 2002], then citing the complete source in your list of references. Use the discovery of prior studies as an opportunity to demonstrate the significance of the problem being investigated and, if applicable, as a means of delineating your analysis from those of others [e.g., the prior study is ten years old and doesn't take into account new variables]. Strategies for responding to prior research can include: stating how your study updates previous understandings about the topic, offering a new or different perspective, applying a different or innovative method of gathering and interpreting data, and/or describing a new set of insights, guidelines, recommendations, best practices, or working solutions.

3. What should I do if I want to use an adapted version of someone else's work? You still must cite the original work. For example, you use a table of statistics from a journal article published in 1996 by author Smith, but you have altered or added new data to it. Reference the revised chart, such as, [adapted from Smith, 1996], then cite the original source in your list of references. You can also use other terms in order to specify the exact relationship between the original source and the version you have presented, such as, "based on data from Smith [1996]...," or "summarized from Smith [1996]...." Citing the original source helps the reader locate where the information was first presented and under what context it was used as well as to evaluate how effectively you applied it to your own research.

4. What should I do if several authors have published very similar information or ideas? You can indicate that the topic, idea, concept, or information can be found in the works of others by stating something similar to the following example: "Though many scholars have applied rational choice theory to understanding economic relations among nations [Smith, 1989; Jones, 1991; Johnson, 1994; Anderson, 2003; Smith, 2014], little attention has been given to applying the theory to examining the influence of non-governmental organizations in a globalized economy." If you only reference one author or only the most recent study, then your readers may assume that only one author has published on this topic, or more likely, they will conclude that you have not conducted a thorough review of the literature. Referencing all relevant authors of prior studies gives your readers a clear idea of the breadth of analysis you conducted in preparing to study the research problem. If there has been a significant number of prior studies on the topic [i.e., ten or more], describe the most comprehensive and recent works because they will presumably discuss and reference the older studies. However, note in your review of the literature that there has been significant scholarship devoted to the topic so the reader knows that you are aware of the numerous prior studies.

5. What if I find exactly what I want to say in the writing of another researcher? In the social sciences, the rationale in duplicating prior research is generally governed by the passage of time, changing circumstances or conditions, or the emergence of variables that necessitate new investigations . If someone else has recently conducted a thorough investigation of precisely the same research problem that you intend to study, then you likely will have to revise your topic, or at the very least, review this literature to identify something new to say about the problem. However, if it is someone else's particularly succinct expression, but it fits perfectly with what you are trying to say, then you can quote from the author directly, referencing the source. Identifying an author who has made the exact same point that you want to make can be an opportunity to validate, as well as reinforce the significance of, the research problem you are investigating. The key is to build on that idea in new and innovative ways. If you are not sure how to do this, consult with a librarian .

6. Should I cite a source even if it was published long ago? Any source used in writing your paper should be cited, regardless of when it was written. However, in building a case for understanding prior research about your topic, it is generally true that you should focus on citing more recently published studies because they presumably have built upon the research of older studies. When referencing prior studies, use the research problem as your guide when considering what to cite. If a study from forty years ago investigated the same topic, it probably should be examined and considered in your list of references because the research may have been foundational or groundbreaking at the time, even if its findings are no longer relevant to current conditions or reflect current thinking [one way to determine if a study is foundational or groundbreaking is to examine how often it has been cited in recent studies using the "Cited by" feature of Google Scholar ]. However, if an older study only relates to the research problem tangentially or it has not been cited in recent studies, then it may be more appropriate to list it under further readings .

7. Can I cite unusual and non-scholarly sources in my research paper? The majority of the citations in a research paper should be to scholarly [a.k.a., academic; peer-reviewed] studies that rely on an objective and logical analysis of the research problem based on empirical evidence that reliably supports your arguments. However, any type of source can be considered valid if it brings relevant understanding and clarity to the topic. This can include, for example, non-textual elements such as photographs, maps, or illustrations. A source can include materials from special or archival collections, such as, personal papers, manuscripts, business memorandums, the official records of an organization, or digitized collections. Citations can also be to unusual items, such as, an audio recording, a transcript from a television news program, a unique set of data, or a social media post. The challenge is knowing how to cite unusual and non-scholarly sources because they often do not fit within consistent citation rules of books or journal articles. Given this, consult with a librarian if you are unsure how to cite a source.

NOTE:   In any academic writing, you are required to identify which ideas, facts, thoughts, concepts, or declarative statements are yours and which are derived from the research of others. The only exception to this rule is information that is considered to be a commonly known fact [e.g., "George Washington was the first president of the United States"] or a statement that is self-evident [e.g., "Australia is a country in the Global South"]. Appreciate, however, that any "commonly known fact" or self-evidencing statement is culturally constructed and shaped by specific social and aesthetical biases . If you have any doubt about whether or not a fact is considered to be widely understood knowledge, provide a supporting citation, or, ask your professor for clarification about whether the statement should be cited.

Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers . 7th edition. Boston, MA: Pearson, 2012; Blum, Susan Debra. My Word!: Plagiarism and College Culture . Ithaca, NY: Cornell University Press, 2009; Bretag, Tracey., editor. Handbook of Academic Integrity . Singapore: Springer Singapore, 2020; Carlock, Janine. Developing Information Literacy Skills: A Guide to Finding, Evaluating, and Citing Sources . Ann Arbor, MI: University of Michigan Press, 2020; Harvard Guide to Using Sources. Harvard College Writing Program. Harvard University; How to Cite Other Sources in Your Paper. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Lunsford, Andrea A. and Robert Connors; The St. Martin's Handbook . New York: St. Martin's Press, 1989; Mills, Elizabeth Shown. Evidence Explained: Citing History Sources from Artifacts to Cyberspace . 3rd edition. Baltimore, MD: Genealogical Publishing Company, 2015; Research and Citation Resources. The Writing Lab and The OWL. Purdue University; Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Why Cite? Poorvu Center for Teaching and Learning, Yale Univeraity.

Other Citation Research Guides

The following USC Libraries research guide can help you properly cite sources in your research paper:

• Citation Guide

The following USC Libraries research guide offers basic information on using images and media in research:

Listed below are particularly well-done and comprehensive websites that provide specific examples of how to cite sources under different style guidelines.

• Purdue University Online Writing Lab
• Southern Cross University Harvard Referencing Style
• University of Wisconsin Writing Center

This is a useful guide concerning how to properly cite images in your research paper.

• Colgate Visual Resources Library, Citing Images

This guide provides good information on the act of citation analysis, whereby you count the number of times a published work is cited by other works in order to measure the impact of a publication or author.

Measuring Your Impact: Impact Factor, Citation Analysis, and other Metrics: Citation Analysis [Sandy De Groote, University of Illinois, Chicago]

Automatic Citation Generators

The links below lead to systems where you can type in your information and have a citation compiled for you. Note that these systems are not foolproof so it is important that you verify that the citation is correct and check your spelling, capitalization, etc. However, they can be useful in creating basic types of citations, particularly for online sources.

• BibMe -- APA, MLA, Chicago, and Turabian styles
• DocsCite -- for citing government publications in APA or MLA formats
• EasyBib -- APA, MLA, and Chicago styles
• Son of Citation Machine -- APA, MLA, Chicago, and Turabian styles

NOTE:   Many companies that create the research databases the USC Libraries subscribe to, such as ProQuest , include built-in citation generators that help take the guesswork out of how to properly cite a work. When available, you should always utilize these features because they not only generate a citation to the source [e.g., a journal article], but include information about where you accessed the source [e.g., the database].

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• URL: https://libguides.usc.edu/writingguide

August 6, 2024

For the Record- August 6, 2024: DCTI Resources, Conversion of Paper External Reliance Records

In this Issue:

Diversity in Clinical Trials: Building a Community-Based Research Collaboratory

Diversity in clinical trials town halls, conversion of paper external reliance records to zipline.

The UW Office of Healthcare Equity (OHCE) is leading the University’s efforts to establish the necessary infrastructure to support implementation of the community engagement aspects of WA State’s new Diversity in Clinical Trials law ( RCW 69.78 ). One component of their efforts is the development of a Community-Based Research Collaboratory (CBRC). This innovative approach will empower community members to actively participate in shaping research agendas and priorities for the University.

CBRC Vision:

• Center community voices: By involving community members from the outset, the CBRC aims to create a truly patient-centered research process.
• Address health disparities: The CBRC will focus on chronic diseases disproportionately affecting marginalized communities.
• Build partnerships: Collaborating with community organizations is essential to building trust and driving meaningful change.
• Enhance researcher access: By streamlining community engagement resources and processes, researchers gain best practices across the research lifecycle.

Building the Foundation: OHCE has initiated discussions with community-based organizations to foster strong partnerships. These collaborations are crucial for understanding community needs and co-creating research projects that address their priorities.

To support this critical work, OHCE is expanding their team and hiring a Community Engagement Specialist and a Director by the end of the year. These dedicated roles will strengthen the University’s capacity to build relationships, support community-led initiatives, and advance CBRC goals.

More information about the CBRC and other OHCE initiatives to facilitate researcher engagement with underrepresented communities will be presented at the September 20th virtual town hall meeting.

Registration for the September 4, 2024 (9:00-10:30am Pacific Time), virtual town hall meeting regarding the UW’s Diversity in Clinical Trials Initiative is now open. This event is intended to provide researchers and other interested parties with the opportunity to ask questions and provide feedback on the soon to be published draft diversity plan and associated guidance. A special mid-August HSD e-newsletter will announce when these documents are available.

The event will begin with a 30-minute overview presentation, followed by a 60-minute Q&A. Attendees are encouraged to submit in advance any questions they would like addressed using the Contact Us form on the UW DCTI website . For those unable to attend, a post-session recording will be available.

There will be another town hall meeting on Friday, September 20, 2024, 2:00-3:30pm Pacific Time, which will focus on the UW’s plans for providing translation and interpreter services as well as supporting community engagement. More information regarding this event will be published in our September e-newsletter.

Notice and Request for Review

HSD’s Reliance Team continues to manage approximately 150 paper applications for reliance on a non-UW IRB. HSD now plans to convert these applications into Zipline over the next 6 months. In contrast to previous waves of study conversions, this process will require little to no involvement of study teams.

To convert these applications, HSD’s Reliance Team will:

• Create a shell application in Zipline with the information that HSD already has available, and
• Upload all documentation that it has for the application to the shell application, and
• Send a Zipline notification to the PI of the application that it has been converted along with instructions for how to manage the application.

HSD may contact individual study teams if additional information is required to complete the conversion process.

Because HSD has extremely limited information about these applications, only the PI will be listed on the application.

What should PIs do? When the PI receives a notification, they should review the Zipline content for accuracy and contact HSD immediately if any of the following apply:

• There is a change in UW PI, or
• There is a change to the reviewing IRB, or
• There is a proposal to use eConsent.

Otherwise, no action is needed.

Because these applications are created with the limited information that HSD has, most of the SmartForm questions will be blank and typically required documentation will not be present. Initiating a modification or study update will trigger system requirements to answer all Smartform questions, even if those questions are not relevant to the modification. Because of this, HSD does not require that these applications be “brought into line” with current documentation requirements and strongly discourages study teams from modifying the application except for the reasons noted above. PIs will receive annual notifications about the status of the application, as they would for any external reliance applications, and should close the application when it is closed by the non-UW IRB.

For questions about the conversion plan or how to manage these applications, contact [email protected] .

University of Washington Office of Research

Or support offices.

• Human Subjects Division (HSD)
• Office of Animal Welfare (OAW)
• Office of Research (OR)
• Office of Research Information Services (ORIS)
• Office of Sponsored Programs (OSP)

OR Research Units

• Applied Physics Laboratory (APL-UW)
• WA National Primate Research Center (WaNPRC)

Research Partner Offices

• Corporate and Foundation Relations (CFR)
• Enivronmental Health and Safety (EH&S)
• Grant and Contract Accounting (GCA)
• Institute of Translational Health Sciences (ITHS)
• Management Accounting and Analysis (MAA)
• Post Award Fiscal Compliance (PAFC)

Collaboration

• Centers and Institutes
• Collaborative Proposal Development Resources
• Research Fact Sheet
• Research Annual Report
• Stats and Rankings
• Honors and Awards
• Office of Research

© 2024 University of Washington | Seattle, WA

In-Text Citations

In scholarly writing, it is essential to acknowledge how others contributed to your work. By following the principles of proper citation, writers ensure that readers understand their contribution in the context of the existing literature—how they are building on, critically examining, or otherwise engaging the work that has come before.

APA Style provides guidelines to help writers determine the appropriate level of citation and how to avoid plagiarism and self-plagiarism.

We also provide specific guidance for in-text citation, including formats for interviews, classroom and intranet sources, and personal communications; in-text citations in general; and paraphrases and direct quotations.

Academic Writer ®

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Teaching APA Style? Become a course adopter of the 7th edition Publication Manual

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Open Access

Peer-reviewed

Research Article

On the possible use of hydraulic force to assist with building the step pyramid of saqqara

Roles Conceptualization, Data curation, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected] , [email protected]

Affiliation Paleotechnic., Paris, France

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Validation, Visualization, Writing – original draft, Writing – review & editing

Affiliation Univ. Grenoble Alpes, INRAE, CNRS, IRD, Grenoble INP, IGE, Grenoble, France

Roles Conceptualization, Investigation, Methodology, Software, Visualization

Affiliation Sicame Group, Arnac-Pompadour, France

Roles Conceptualization, Investigation, Methodology, Validation, Writing – review & editing

Affiliation CEDETE—Centre d’études sur le Développement des Territoires et l’Environnement, Université d’Orléans, Orléans, France

Roles Conceptualization, Investigation, Methodology, Validation

Roles Conceptualization, Investigation, Methodology, Visualization

Affiliation AtoutsCarto, Bourges, France

Roles Methodology, Project administration

Affiliation Verilux International, Brienon-sur-Armançon, France

Roles Conceptualization, Investigation, Validation, Writing – review & editing

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Validation

Roles Conceptualization, Investigation, Methodology, Supervision, Validation

• Xavier Landreau, 
• Guillaume Piton, 
• Guillaume Morin, 
• Pascal Bartout, 
• Laurent Touchart, 
• Christophe Giraud, 
• Jean-Claude Barre, 
• Cyrielle Guerin, 
• Alexis Alibert, 
• Charly Lallemand

• Published: August 5, 2024
• https://doi.org/10.1371/journal.pone.0306690
• Reader Comments

The Step Pyramid of Djoser in Saqqara, Egypt, is considered the oldest of the seven monumental pyramids built about 4,500 years ago. From transdisciplinary analysis, it was discovered that a hydraulic lift may have been used to build the pyramid. Based on our mapping of the nearby watersheds, we show that one of the unexplained massive Saqqara structures, the Gisr el-Mudir enclosure, has the features of a check dam with the intent to trap sediment and water. The topography beyond the dam suggests a possible ephemeral lake west of the Djoser complex and water flow inside the ’Dry Moat’ surrounding it. In the southern section of the moat, we show that the monumental linear rock-cut structure consisting of successive, deep compartments combines the technical requirements of a water treatment facility: a settling basin, a retention basin, and a purification system. Together, the Gisr el-Mudir and the Dry Moat’s inner south section work as a unified hydraulic system that improves water quality and regulates flow for practical purposes and human needs. Finally, we identified that the Step Pyramid’s internal architecture is consistent with a hydraulic elevation mechanism never reported before. The ancient architects may have raised the stones from the pyramid centre in a volcano fashion using the sediment-free water from the Dry Moat’s south section. Ancient Egyptians are famous for their pioneering and mastery of hydraulics through canals for irrigation purposes and barges to transport huge stones. This work opens a new line of research: the use of hydraulic force to erect the massive structures built by Pharaohs.

Citation: Landreau X, Piton G, Morin G, Bartout P, Touchart L, Giraud C, et al. (2024) On the possible use of hydraulic force to assist with building the step pyramid of saqqara. PLoS ONE 19(8): e0306690. https://doi.org/10.1371/journal.pone.0306690

Editor: Joe Uziel, Israel Antiquities Authority, ISRAEL

Received: December 7, 2023; Accepted: June 22, 2024; Published: August 5, 2024

Copyright: © 2024 Landreau et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files. The computer codes are available upon request.

Funding: The Sicame Group, The Atoutscarto Company and The Verilux Company provided support in the form of salaries for GM, CG and J-CM, respectively. The specific roles of these authors are articulated in the ‘author contributions’ section.

Competing interests: The authors have read the journal’s policy and have the following competing interests: GM, CG and J-CM are paid employees of The Sicame Group, The Atoutscarto Company and The Verilux Company, respectively. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

1 Introduction

The funerary complex of King Djoser, built at Saqqara in Egypt around 2680 B.C., is considered a significant milestone in monumental architecture. It is the first to disclose two crucial innovations: a pyramid shape for the pharaoh’s grave and the exclusive use of fully dressed stones for masonry. In practice, it is also revolutionary in the ability to extract and raise stones by millions before stacking them with precision [ 1 ]. Djoser’s complex visible achievements are such that its architect, Vizier, and Great Priest of Ra, Imhotep, was deified by the New Kingdom.

The knowledge and innovations implemented in the Djoser mortuary complex profoundly influenced future developments and were widely perfected throughout the Old Kingdom’s III rd and IV th Dynasties, i . e . circa 2680–2460 B.C. These developments resulted in a substantial increase in the megaliths’ size [ 2 ], leading to pyramids of spectacular dimensions, such as those of the Meidum, Dahshur, and Giza plateaus. In less than 150 years, the average weight of the typical large stones was thus multiplied by ≈8 and went from ≈300 kg for Djoser’s pyramid to more than 2.5 tons for Chephren’s pyramid’s structural blocks [ 3 ]. For the largest lintels, the weight increases by two orders of magnitude, with several blocks of ≈50 – 100 tons for Cheops’ pyramid. On this short timeframe on the scale of human history, Egyptians carried and raised some 25 million tons of stones [ 4 ] to build seven monumental pyramids. Assuming an annual work schedule of 300 days at a rate of 10 hours/day, meaning 450,000 hours spread over less than 150 years, this requires a technical and logistical organization capable, on average, of cutting, moving, and adjusting about 50 tons of stone blocks per hour. Even if one admits that not every pyramid’s blocks are fitted with millimeter precision, the amount of work accomplished is truly remarkable. Interestingly, the pyramids later built in Egypt tended to be smaller with time and never reached the volume of the Old Kingdom’s monumental structures again.

As authentic sources from the working sphere of pyramid architects are currently lacking, no generally accepted wholistic model for pyramid construction exists yet. Although many detailed publications dedicated to pyramid-building procedures have given tangible elements [ 5 , 6 ], they usually explain more recent, better documented, but also smaller pyramids [ 7 ]. These techniques could include ramps, cranes, winches, toggle lifts, hoists, pivots, or a combination of them [ 8 – 10 ]. Studies of the pyramid’s construction sites also revealed a high level of expertise in managing the hydraulic and hydrological environment, such as utilizing waterways to deliver materials, constructing ports and locks, or setting up irrigation systems [ 11 , 12 ]. These achievements have led some scholars to refer to ancient Egypt as an ‘early hydraulic civilization [ 11 ].’ However, there is actually very little multidisciplinary analysis combining the rich archaeological findings on pyramids with other disciplines such as hydrology, hydraulics, geotechnics, paleoclimatology, or civil engineering [ 9 ]. Therefore, the topic of water force in the context of pyramid construction remains insufficiently addressed in the academic literature.

Moreover, a second question accentuates the enigma: the Pharaohs who built these pyramids are missing. Until now, neither written record nor physical evidence reports the discovery of one of the III rd and IV th Dynasties’ Pharaohs. Old Kingdom’s ‘big’ pyramids’ rooms were allegedly plundered [ 13 – 15 ] during the millennia that followed the construction of the pyramids, leaving little evidence behind [ 12 ]. The III rd and IV th Dynasties’ rooms present little or no funerary attributes, such as those observed in other high-dignitary figures’ tombs contemporary to the period [ 16 , 17 ], with no King’s remains found inside. In addition, the walls of the pyramids’ chambers do not exhibit any hieroglyphs, paintings, engravings, or drawings, which would allow us to qualify them as funerary with certainty. Despite this lack of evidence, many authors [ 18 ] still support that these rooms can be attributed to Pharaohs’ burials mainly based on royal cartouches or Kings’ names found elsewhere within the pyramid or nearby temples.

Over the recent years, Dormion & Verd’Hurt [ 19 , 20 ], Hamilton [ 21 – 24 ] or others [ 1 , 25 ] were among the first to consider possible non-funerary functions of pyramids’ internal layouts by pointing out some architectural inconsistencies and highlighting the high degree of complexity of several structures, irrelevant for a burial chamber. Their analysis provided both chambers and gallery systems with a technical dimension, emphasizing a level of engineering on the part of the ancient builders that is quite remarkable and sometimes challenges any apparent explanation. This technical level is at once reflected in the geometry of the rooms and ducts, as well as in the stonework, which includes materials selection, extraction, cutting, and then assembling with exceptional accuracy [ 20 ]. This precision involved several advanced sub-techniques, such as inter-block mortar joint realization [ 26 – 29 ] or stone polishing with flatness and roughness values that reach levels of contemporary know-how. Apart from surfaces and interfaces, the builders’ technical ability is also evident throughout sophisticated mechanical systems set up in the pyramids [ 30 ], as swivel stone flaps’ designs in the Meidum and Bent pyramids [ 21 , 24 ] or tilted portcullises found in the Bent pyramid, as well as at Giza [ 20 ]. These elements suggest that, rather than an aesthetic rendering or a funerary use for these layouts, ancient Egyptians intended technical functions for some walls, tunnels, corridors, shafts, and chambers where more straightforward existing techniques were insufficient.

In summary, the analysis of the pyramids’ construction and the investigation of their internal layouts seem to require more research to provide a wholistic explanation to their purpose. This study aims to provide a fresh look at these topics by applying an alternative, multi-disciplinary, wholistic approach. It revisits the Old Kingdom’s pyramids’ construction methodology and seeks to explain the significance of internal layouts during construction. Based on current archaeological knowledge, we demonstrate that the Saqqara’s topography and the layout of several structures are consistent with the hypothesis that a hydraulic system was used to build the pyramid. The paper is divided into three main sections that analyze the current scientific literature to address the following inquiries: (i) Was the plateau of Saqqara supplied with water? (ii) If so, how was it possibly stored and treated? and (iii) How was it used to build the pyramid? A discussion and some concluding remarks and perspectives follow.

2 The saqqara’s hydrologic network

Our study began with the postulate that the larger Cheops’ and Chephren’s pyramids of Giza plateau were the outcomes of technical progress from previous pyramids, with the Step Pyramid as a technological precursor. While many literature studies focus on the construction of Cheops’ pyramid, we found it more relevant to examine the building techniques used for the Step Pyramid first. This would provide insight into the processes used by ancient builders that were later refined in subsequent pyramids. As a first approach, we analyzed potential reasons for the specific building of King Djoser’s Complex on the Saqqara Plateau.

2.1 Water resource from the desert wadis

Although detailed measurements of the Nile flood levels have been reported since the V th Dynasty (2480 B.C.) [ 31 – 33 ], there is very little information available about the hydrology of its desert tributaries, known as ’wadis’, in ancient Egypt. Sedimentological evidence of heavy rainfalls and flash floods exists [ 31 , 34 ] but little is known beyond that.

Determining the rainfall regime that the Saqqara region experienced about 4,700 years B.P. is challenging and uncertain. Past studies demonstrated that, from about 11,000 to 5,000 B.P, during the so-called ‘Green Sahara’ period, the whole Sahara was much wetter than today, and the landscape was savannah rather than desert [ 35 , 36 ]. Around 4500–4800 years B.P. too, the Eastern Mediterranean region was wetter than it is now, despite drying up later [ 37 – 39 ]. A range of annual precipitation value of 50–150 mm/year is assumed in the following calculation to perform crude computations of water resource. It covers the range between the >150 mm/year suggested by Kuper & Kropelin [ 40 ] for the end of the Green Sahara period, before the subsequent drier period, during which rainfall decreased to <50 mm/year. The range of variability, i . e . 50 to 150 mm/yr is also consistent with the typical inter-annual rainfall variability observed in the region [ 38 ].

Then, current hydrological monitoring on Egyptian wadis located further to the north and experiencing comparable annual rainfall ( i . e ., 100–200 mm/yr) showed that only 1–3% of this mean annual precipitation was measured as runoff, i.e., surface flows [ 41 ]. This average range is hereafter used for conservative, first-order estimations of available water volume, referred hereafter to as the ‘water resource’. Note that the infrequent, most intense events can reach 50 mm of rainfall and trigger devastating flash floods where the runoff coefficients have been measured up to 30%, i . e ., one order of magnitude higher than the mean annual [ 41 – 43 ]. Note that these water resource and flash flood hydrology estimates neglect that the soils were probably richer in clay and silt just after the Green Sahara period, with several millennia of a wetter climate and savannah landscape [ 35 , 36 ], which would increase the runoff coefficient and available surface water resource in the wadis.

2.2 The Saqqara site: a plateau with a water supply

The Saqqara necropolis is located on a limestone plateau on the west bank of the Nile River, about 180 km from the Mediterranean Sea ( Fig 1 ). The entire site lies in the desert, less than two kilometers from the plateau’s edge (elevation 40–55 m ASL— Above Sea Level ), which overlooks the Nile floodplain (height ≈ 20 m ASL). Further to the west, the desert rises gently for about 20 km (hills’ top elevation ≈ 200–300 m ASL).

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

(Satellite image: Airbus Pléiades, 2021-07-02, reprinted from Airbus D&S SAS library under a CC BY license, with permission from Michael Chemouny, original copyright 2021).

https://doi.org/10.1371/journal.pone.0306690.g001

The reasons behind the construction of the Djoser complex at Saqqara remain unclear. The contribution of economic, socio-political, and religious factors was previously highlighted [ 44 , 45 ], but environmental factors were also possibly influential. In 2020, Wong provided evidence that the climate, geology, and hydrology would have influenced building choices and may have contributed to, or perhaps accelerated, the emergence of stone architecture on the Saqqara plateau [ 37 ].

From a geological standpoint, the layered structure of the limestone at Saqqara was indeed stressed as a favorable factor for excavating large amounts of construction stones [ 46 , 47 ]. These layers, which consist of 30–60 cm thick sand-rich calcareous beds alternated with calcareous clay and marl layers, made it easy to extract the limestone blocks from their parent beds by vertical cuttings, the original thickness being reflected in the building stones’ thickness of Djoser’s complex.

From a hydrological standpoint, the Abusir wadi is considered a second environmental factor that strongly influenced the Early Dynastic development of the Saqqara necropolis at least [ 45 , 48 – 50 ]. The Abusir wadi is the ephemeral stream draining the hills west of Saqqara ( Fig 1 ) . Before this study, academic research mainly focused on the downstream part of the wadi [ 45 , 48 – 50 ], namely the Abusir Lake [ 51 ] located north of Saqqara Plateau. However, the upstream portion has remained undocumented.

In order to analyze the relationships between the Abusir wadi and the Step Pyramid’s construction project, the drainage networks west of the Saqqara area were mapped for the first time to the best of our knowledge, using various satellite imagery ( Fig 1 ) and Digital Elevation Models (see S1 Fig in S2 File ).

A paleo-drainage system can be identified upstream of the Gisr el-Mudir structure as the origin of the Abusir wadi ( Fig 1 , pink line). The boundaries of this runoff system form a catchment area never reported so far, although easily recognizable from the geomorphological imprints of surface paleochannels in the desert and on historical maps [ 52 ]. Although it currently has a 15 km 2 surface area, we cannot rule out the possibility that the drainage divides shifted and changed due to land alterations and aeolian sand deposits over the past 4,500 years.

The current catchment summit is about 110 m ASL, giving the Abusir wadi a 1% average slope over its slightly more than 6 km length. In the field of hydrology, a 1% gradient is described as ‘rather steep’. With such steep slopes, transportation of sand and gravel is expected during flashfloods, which can cause severe downstream damage (scouring or burying of structures, filling of excavations and ponding areas). In comparison, irrigation channels are rather at least ten times less steep (about 0.1%), and the Nile slope is less than 0.01% (less than 200m of elevation gain between Aswan and Cairo).

2.3 The Wadi Taflah: A possible complementary water supply

Reported since the early 1800s, a former tributary to the Nile called the Bahr Bela Ma [ 53 , 54 ] or ‘ Wadi Taflah’ flowed parallel to the Abusir wadi catchment, less than two kilometers south of the Saqqara plateau. From satellite imagery, we identified that the Wadi Taflah arises from a drainage area of almost 400 km 2 and consists of three main branches ( Fig 2 , numbered black dots) still visible from the desert’s geomorphological marks. This network is also visible on the radar imagery provided by Paillou [ 55 ] that can penetrate multiple meters of sand ( S2 Fig in S2 File ). The similarity of the optical and radar drainage patterns confirms the existence and old age of this hydrological network.

https://doi.org/10.1371/journal.pone.0306690.g002

Although no canal was detected from the satellite data, the close proximity of Abusir wadi with the Wadi Taflah ( Fig 2 ) is intriguing and raises the question about a potential ancient, artificial connection between them. According to the 18 th -century maps published by Savary [ 54 ], the Wadi Taflah was ‘closed by an ancient King of Egypt.’ Such a testimony, although imprecise, could suggest the construction of a water diversion by a former ruler. A geophysical investigation could help to find such a structure if existing. The drainage area of Wadi Taflah covers nearly 400 km 2 at an elevation >58 m ASL. This elevation is high enough to allow the diversion of the drainage area toward the Abusir wadi. This would result in an increase in the drained area and associated availability of water resources by a factor of >25 times. Based on the hydrological conditions described in section 2.1, the estimated water resource from Abusir wadi and Wadi Taflah is crudely between 7,500 to 68,000 m 3 /year and 200,000 to 1,800,000 m 3 /year, respectively.

2.4 The Abusir wadi: A structural element in the early dynastic Saqqara’s development

According to the Saqqara topography ( Fig 3 ), the Abusir wadi flowed through the Gisr el-Mudir enclosure before heading north towards the Nile floodplain, where it used to feed an oxbow lake, the Abusir Lake [ 51 ]. With such a localization, the Gisr el-Mudir walls literally dam the Abusir wadi valley’s entire width. The sparse vegetation only growing in the valley bottom upstream of Gisr el-Mudir and not elsewhere in the area evidences this damming and interception of surface and subsurface flows ( Fig 4A , green line). This slight moist area is dominated by plants commonly found in desert margins and wadis, such as Panicum thurgidum and Alhagi graecorum [ 56 ], and is typical of hypodermal flows.

Contour lines extracted from the 1:5,000 topographical map [ 52 ] “Le Caire, sheet H22”.

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a. The Gisr el-Mudir check dam (Satellite image: Airbus Pléiades, 2021-07-02, reprinted from Airbus D&S SAS library under a CC BY license, with permission from Michael Chemouny, original copyright 2021); b.: Digital Elevation Model generated from the 1:5,000 topographical map “Le Caire, sheet H22”.

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Downstream of the Gisr el-Mudir, the Abusir wadi joins the Saqqara Plateau. Its boundaries are defined to the south by an outcropping limestone ridge and to the east by the Sekhemkhet and Djoser’s enclosures ( Fig 3 ).

The landform of this area seems inconsistent with a pure fluvial formation. Instead, the very flat topography on about 2–2.5 km 2 , according to the Saqqara Geophysics Survey Project (SGSP) [ 57 – 60 ] and possibly allowed some ephemeral ponding water which may have resulted in an episodic upper Abusir lake after the most intense rainfalls. However, due to the several-meter deep wind-blown and alluvial sand cover accumulated over the past millennia [ 57 ], the riverbed altitudes during Djoser’s reign are challenging to establish without further investigations, and only broad patterns can be determined from the local topography [ 52 ].

As with many other small wadis, the Early Dynastic hydrology of the Abusir wadi remains largely unknown. According to fluvial sediment analysis in the Abusir Lake area, the Abusir wadi was probably a perennial stream during the Old Kingdom period [ 51 ]. Although the climate is hot and arid nowadays, several studies support a more humid environment during the Old Kingdom [ 34 ] . Multiple strands of evidence indeed suggest that Egypt experienced considerable rainfalls around the reign of Djoser, resulting in frequent flooding and heavy runoffs on the Saqqara Plateau. This climatic feature is supported by sedimentary deposits resulting from flowing water of ‘considerable kinetic force’ contemporary to Djoser’s reign [ 61 , 62 ] . According to Trzciński et al.[ 34 ], the strongly cemented structure L3 found in the Great Trench surrounding the Djoser Complex was due to cyclical watering while the high content of Fe3+ indicates that the region experienced intensive weathering in a warm and humid environment. In 2020, Wong concluded that the ‘ intriguing possibility that the Great Trench that surrounds the Djoser complex may have been filled with water ’ during Djoser’s reign [ 37 ]. If so, this might explain why tombs were built on the northern part of the Saqqara plateau which has a higher altitude [ 45 ] and nothing was constructed inside the Trench until the reign of Userkaf and Unas (V th Dynasty).

3. The saqqara’s water management system

3.1 the gisr el-mudir check dam.

Reported at least since the 18 th century [ 63 ] and extensively described within a decade of a geophysical survey by Mathieson et al ., see also [ 45 ] for a summary, the Gisr el-Mudir is a rectangular enclosure located a few hundred meters west of the Djoser’s complex ( Fig 3 , Fig 4A & 4B ). This monumental structure has a footprint of about 360 m x 620 m, i . e ., larger than the Djoser complex (545 m x 277 m). The walls have an estimated volume of >100,000 m 3 (SGSP, 1992–1993 report), meaning about one-third of the Step Pyramid’s volume. Field inspection and geophysical results from the SGSP [ 57 ] found no construction inside except for a couple of more recent, small graves, thus confirming that the enclosure is mainly empty. Moreover, several elements in the building suggest that this structure predated the Step Pyramid’s complex and was tentatively dated to the late II nd or early III rd Dynasty [ 57 , 64 ], which might turn it into the oldest substantial stone structure in Egypt discovered so far.

Before this study, several conflicting theories about the Gisr el-Mudir’s purpose were put forward [ 59 ]: e . g ., an unfinished pyramid complex (but the lack of a central structure made it improbable to be a funerary monument), a guarded fortress [ 65 ] protecting the Saqqara necropolis from nomadic Bedouin incursions, an embankment to raise a monument to a higher level [ 66 ], a celebration arena [ 64 , 67 ], or even a cattle enclosure. However, given the low level of exploratory work afforded to the structure, no generally accepted explanation exists yet, and its purpose has remained more conjectural than substantiated.

In light of the upstream watershed and its transversal position across the Abusir River, the Gisr el-Mudir’s western wall meets the essential criteria of a check dam, i . e ., a dam intending to manage sediment and water fluxes [ 68 , 69 ]. This comparison is particularly striking regarding its cross-section ( Fig 5 ). According to Mathieson et al . [ 59 ], the basic structure of this wall consists of a hollow construction of two rough-hewn limestone masonry skin-walls, ≈3.2 m high, separated by a 15 m interspace filled with three layers of materials extracted from the surrounding desert bedrock [ 70 ] and cunningly arranged. The first layer ( Fig 5 , ‘ A ’ dot) is made of roughly laid local limestone blocks forming a buttress against the inside of the facing blocks. The secondary fill ( B ) comprises coarse sand and medium to large limestone fragments. Then, the third fill ( C ) consists of rough to fine sand and silt, small limestone fragments, and chippings with pebble and flint nodules. Finally, these A, B, and C backfill layers are positioned symmetrically to the median axis of the wall.

Figure adapted from [ 58 ].

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Civil engineering was used during the Old Kingdom to protect settlements from flash floods, such as the Heit el-Ghurab (’Wall of the Crow’) safeguarding the village of the pyramid builders at Giza [ 71 ]. Regarding the Gisr el-Mudir structure, the abovementioned elements strikingly echo the transversal profile and slope protection of another famous Old Kingdom structure: the Sadd el-Kafara dam built on the Wadi al-Garawi , a colossal building found to be contemporary to that of the Gisr el-Mudir [ 72 – 74 ]. Both structures present the technical signature of zoned earthen dams: a wide embankment made of a central impervious core surrounded by transition filters, i . e ., filling material with coarser grain size, preventing erosion, migration, and potential piping of the core fine material due to seepage. The semi-dressed limestone walls stabilized the inner material and protected it against erosion when water flowed against and above the dam. Both dams have much broader profiles than modern dams. This oversizing could be due to the unavailability of contemporary compaction systems or an empirical and conservative structural design. They both have narrower cores of fine material at the bottom of the dam than at their crest, contradicting modern design [ 75 ]. This can be attributed to the construction phasing that would have started by raising the sidewalls buttressed against the coarse and intermediate filling ( B and C fills in Fig 5 ), followed by a phase of filling the wide core with finer, compacted material [ 72 ].

Finally, the eastern wall’s north-south profile ( Fig 6 , line A-B ) presents a parabolic profile relevant to guide the flows to the basin’s center formed by Gisr el-Mudir. This guidance would have prevented the dam failure by outflanking during flooding events when the dam outlet was saturated. We estimate that the accumulated water crossed the dam through an outlet likely located at the valley’s lowest elevation, i . e ., near 48.7 m ASL ( G1 in Figs 4B and Fig 6 ). In summary, the Gisr el-Mudir’s western wall likely acted as a first check dam to the Abusir wadi flows.

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The excavations performed on the eastern wall of the Gisr el-Mudir highlighted a lower structural quality [ 45 ]. Its shape is similar to that of the western wall, with a distinctive parabolic profile ( Fig 6 , line C-D ). Furthermore, it discloses two topographical singularities: first, its overall altitude is a few meters lower than the western wall ( Fig 7A ). Then, in the southern part of the eastern wall, a geophysics anomaly ( G2 in Figs 4B and Fig 6 ) was found to be a series of massive, roughly cut, ‘L’-shaped megaliths [ 45 , 66 ]. Before our study, these megaliths were thought to possibly be the remains of a monumental gateway–due to their similarities with the Djoser’s complex enclosure’s entrance–but their purpose was not specified [ 66 ]. According to our analysis, these megaliths could be the side elements of the water outlets, possibly slit openings [ 76 ] that were likely closed off by wood beams but could be opened to drain the basin. They are consistently found near a trench that is 2.2 m deep [ 45 ], which we believe is possibly the canal that guided outflowing water. In a nutshell, the eastern wall likely acted as a second check dam to the Abusir flows.

a. West-east elevation profile of the Gisr el-Mudir structure. b: Schematic reconstitution of the profile with water flow.

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In addition to the two dams formed by the western and eastern walls, the Gisr el-Mudir enclosure forms a basin ( Fig 4 ). It is closed to the north by another wall made of limestone blocks, though not very tall (likely <2m) because it is built on a natural ridge [ 45 ]. The basin’s southern boundary is also mostly made of a natural ridge. The possible absence of a masonry wall on certain portions on this side was unexplained by previous analyses [ 45 ]. However, it makes perfect sense when considering a reservoir function. Anchoring dams against side slopes is indeed the standard approach to guide flows and prevent outflanking [ 68 ].

In essence, the Gisr el-Mudir enclosure exhibits the defining features of a check dam ( Fig 7B ). The catchment it intercepts is large enough (15 km 2 ), plus eventual water derivation from the Wadi Taflah to produce flash floods transporting significant amounts of gravel, sand, mud, and debris due to its slope during intense rainfalls. The valley upstream of the western wall likely served as a first reservoir where the coarsest gravels tended to deposit. The overflowing water then filled the inner basin of the Gisr el-Mudir, where coarse sand would again deposit. Assuming a storage depth between 1 and 2 meters, the retention capacity of the basin would be approximately 220,000–440,000 m 3 . This volume is in line with the overall water volume of a flash flood that could be produced by the Abusir wadi, which is estimated to be about 75,000–225,000 m 3 , assuming 50 mm of rainfall and a 0.30 runoff coefficient. This key, first structure of the Saqqara hydraulic system would have then delivered clear water downstream in normal time, as well as muddy water with an eventually suspended load of fine sand and clay during rainfall events.

3.2 The deep Trench’s water treatment system

3.2.1 general configuration..

The Djoser’s Complex is surrounded by a vast excavation area, commonly referred to as the ’Dry Moat’ since Swelim spotted its outlines [ 77 , 78 ] ( Fig 3 , blue strip). The Dry Moat is alleged to be a continuous trench cut in the bedrock, up to 50 m wide and ≈3 km long, enclosing an area of ≈600 m by ≈750 m around the Djoser complex [ 77 , 79 , 80 ]. When considering an average depth of 20 m for the four sides of the trench [ 61 ], the total excavated volume is estimated at ≈3.5 Mm 3 , approximately ten times the Step Pyramid‘s volume. Due to the thick cover of sand and debris [ 61 ] accumulated over the past millennia, its precise geometry is incompletely characterized. The moat’s east and south channels are particularly debated [ 61 ].

According to Swelim, the moat’s south channel probably split into two parts, known as the Inner and Outer south channels [ 78 ] ( Fig 8 , blue strips). The Inner south channel is relatively shallow (5–7 m deep), 25–30 m wide, and spans approximately 350 m parallel to the southern wall of Djoser’s complex.

Water from the Abusir Lake can follow two parallel circuits.

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The ‘Deep Trench’ [ 81 ] ( Fig 8 , red rectangles and dotted lines) is built inside the Inner south channel, along its south wall. It is a ≈27 m-deep, 3 m-wide, and hundreds of meter-long rock-cut channel with several ‘compartments’. So far, only about 240 m [ 78 ] of its probable 410 m length have been subject to archaeological excavations in 1937–1938 [ 78 ], 1937–1945 [ 81 ], and 1975 [ 82 ]. Consequently, approximately 170 m remains unexplored, mainly due to the presence of the later Old Kingdom two groups of mastabas built above the trench and at risk of collapse if submitted to underground excavation (transparent grey parts in Fig 8 ).

Generally, two leading theories are highlighted in the literature to explain the purpose of the trench: (i) a quarry for the Djoser’s complex [ 47 , 83 ], or (ii) a spiritual function [ 78 , 84 , 85 ]. However, over recent years, authors have pointed out several specificities in the trench’s architectural layout, which seem irrelevant in a religious or mining context [ 1 , 86 , 87 ]. In particular, on the mining aspect, several authors estimate [ 45 , 86 ] that the form of the track suggests that the extraction of stones was not its sole or even primary function, as it does not match with the ancient Egyptian quarrying methods. Reader also considers that some parts of the trench which are ~27 m deep and covered with a rocky ceiling, are wholly unrealistic for quarrying operations and unlikely to have required the paving found near the trench’s bottom [ 45 ]. This point is further emphasized by the narrow width of the excavated Deep Trench (3m), which is impractical in a mining scenario.

On the spiritual aspect, Kuraszkiewicz suggests that the trench may have developed a ritual significance as a gathering place for the souls of the nobles to serve the dead King [ 86 ]. Monnier [ 1 ] considers that the discovery of several niches in the channel does not fully demonstrate the moat’s religious purpose and considers it secondary. The trench’s ritual significance is also regarded as secondary by Reader [ 45 ], who suggests the ritual aspects developed only after the complex’s construction and do not reflect the original function of the structure.

In 2020, based on the archaeological, geological, and climatic evidence, Wong was the first to introduce the idea that the trench may have had a completely different function, being filled with runoff water following downpours [ 37 ]. If so, this would explain why it was not until the reigns of Unas and Userkaf (V th Dynasty) that new graves occupied the moat. The onset of drier climatic conditions [ 31 , 88 ] around the end of the IV th Dynasty would have created more favorable conditions for new constructions inside the moat. Despite the potential impact of Wong’s assumption, it did not receive much attention in the literature. Nonetheless, the current authors believe that Wong’s conclusions make sense when considering Saqqara’s downstream localization of a watershed.

3.2.2 The deep Trench: A series of rock-cut compartments built in a hydrological corridor.

The Inner south channel and the Deep Trench are built inside the Unas Valley, a hydrological corridor connecting the Abusir wadi plain to the Nile floodplain ( Fig 3 ). Both were thus possibly submitted to (un)controlled flooding [ 34 , 61 ] from the Abusir wadi plain.

The Deep Trench connects at least three massive subterranean compartments [ 45 , 47 ] ( Fig 8 , red parts) meticulously carved out with precisely cut surfaces [ 78 ] ( Fig 9 ) and joined by a tunnel [ 77 ] . A fourth compartment, retroactively named compartment-0 ( Fig 10 ), likely exists [ 45 , 78 ]. On a large scale, the perfect geometric alignment of these compartments is remarkable, as well as their parallelism with the Djoser’s complex and their bottom level similar to those of the southern and northern shafts (≈27 m ASL). These spatial relationships have led some authors to consider that the trench was created as a part of Djoser’s Complex [ 86 , 89 , 90 ]. This assumption has been reinforced by Deslandes’ discoveries of at least two east-west pipes, about 80 m long, connecting the Djoser’s Complex’s subterranean layouts to the Dry Moat’s eastern side [ 91 ].

a: View from the west; b: View from the east. The workers in the background provide a sense of the structure’s immense scale and technicity.

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View of the south face.

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Taken together, the Deep Trench architecture highlights technical proficiency and suggests that the ancient Egyptians intended a technical function rather than a spiritual one. Surprisingly, despite the available clues, the Deep Trench has never undergone detailed engineering studies to analyze its features and identify its purpose. The following sections suggest a hydraulic rationale behind the trench’s internal layout (more details in the Supplement ).

3.2.3 Consistency of the Deep Trench architecture with a water treatment system.

Being largely described in the literature [ 77 , 86 , 92 ] , the compartments’ layouts are presented in detail in the Supplement . Considering its architecture and geographical location, the Dry Moat’s southern section combines the technical requirements of a water treatment system, including sedimentation, retention, and purification. Fig 10 illustrates a comprehensive outline of the installation’s functioning process. Similarly to the Gisr el-Mudir, we found that the Deep Trench compartments likely served to transfer water with low suspended sediment concentration to the downstream compartments by overflowing. The process of using a series of connected tanks to filter water and remove sediment is an ancient technique that has been extensively documented in archaeological and scientific literature [ 93 – 96 ]. This method has been employed for centuries to clean water and has played a significant role in the development of water treatment practices.

Compartment-0 presents the minimum requirements of a settling basin (considerable length and width, low entry slope, position at the entry of Unas hydrological corridor) whose purpose is to facilitate the coarse particles’ settling that would overflow from Gisr el-Mudir during heavy rainfalls. The descending ramp along the south wall identified by Swelim [ 97 ] may have permitted workers to dredge the basin and remove the accumulated sediments along the east wall ( Fig 10 ) . The very probable connection [ 45 , 97 ] between compartment-0 and compartment-1, blocked with rough masonry ( Fig 9B and S3 Fig in S2 File ), is consistent with an outlet overflowing structure. Additionally, when the flow rate in compartment-0 was too high, the tunnel or even the northern portion of the trench may have been used as a spillway bypass to evacuate excess water toward the eastern portion of the Unas wadi valley ( Fig 8 , safety circuit).

Compartment-1 is then consistent with a retention basin with > 3000 m 3 capacity ( Fig 10 , left part). The bottom stone paving with mortar joints probably limited water seepage through the bedrock. Its eastern end could go until the compartment-2 [ 45 ] to form a single compartment, but this point remains debated [ 78 , 97 ] .

Compartment-2’s is, unfortunately, largely unexplored ( Fig 10 ). Its downstream position might indicate a second retention basin or possibly an extension [ 45 ] of the first one. The western part of this compartment (stairs area) perfectly aligns with the base levels of the Djoser’s complex south and north shafts, which points towards a connection between the three [ 86 ] . If so, it would be aligned with the recently discovered pipe of a 200 m-long tunnel linking the bottom of Djoser’s Complex’s southern and northern shafts [ 91 ] (see next section, Fig 11 ). Compartment-2 would then be another, or an extended, retention basin equipped with a water outlet toward the north.

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Compartment-3 ( Fig 10 , right part) is likely a side purification basin for drinking water. Its position as an appendix of the primary water circuit connecting Gisr el-Mudir to Djoser’s complex seems optimal to minimize water circulation and maximize water-settling time, thus increasing its purification. The second and third sections likely allowed further settling of particles and would have served as reservoirs during dry periods. The relatively smooth walls of the whole structure would have hindered the growth of microbes, plants, and other contaminants, thereby helping maintain the water’s cleanliness [ 98 ] . Four surface wells allowed access to the end of the last compartment where the water, kept clear and fresh in the shadow of this subterranean monumental cistern, could be used by the building site workforce [ 99 ] .

The excavated volume of the Deep Trench is greater than 14,000 m 3 [ 77 , 86 , 92 ]. If we assume that most of the water available in the Wadi Taflah was diverted toward Saqqara, this volume could be filled about a dozen to more than one hundred times per year on average. We hypothesize a typical filling level of 45 m ASL in the Deep Trench, but an accurate topographical survey is lacking, and the maximum water level could vary between 40–52 m ASL, according to the surrounding terrain elevation.

In essence, we discovered and highlighted for the first time that the Deep Trench’s position and design are consistent with possible use as a water treatment and storage system capable of cleaning and storing thousands of cubic meters of water.

4. The central hydraulic lift system

4.1 overview of the djoser’s complex’ substructure.

The internal and external architecture of the Djoser’s Complex is thoroughly documented [ 1 , 3 , 100 , 101 ]. The Supplement provides an overview of this structure. Basically, the six-step Step Pyramid itself stands slightly off-center in a rectangular enclosure toward the south and reaches a height of approximately 60 m ( Fig 11 ). The pyramid consists of more than 2.3 million limestone blocks, each weighing, on average [ 2 ], 300 kg, resulting in a total estimated weight of 0.69 million tons and a volume of ≈330,400 m 3 .

The substructure features at least 13 shafts, including two significantly sizeable twin shafts located at the north and south of the complex ( Fig 11 , insets 3&4), and an extensive and well-organized network of galleries descending up to 45 m below ground level [ 102 ]. The north shaft is surrounded by four comb-shaped structures distributed on each side and angled 90° apart. Ground Penetrating Radar (GPR) revealed that the twin shaft layouts are connected [ 91 , 102 ] by a 200 m-long tunnel. Moreover, at least two of the twelve shafts on the pyramid’s east side are connected to the supposed eastern section of the Dry Moat by two 80 m long pipes ( Fig 11 and Supplement ).

From our 3D models, we estimate that ancient architects extracted more than 30,000 tons of limestone from the bedrock to dig the whole underground structure. The total length of the tunnels and subterranean rooms combined is ~6.8 km. However, its layout and purpose remain primarily poorly known and debated [ 6 ].

4.2 The connected twin shafts

The ‘north shaft’ is located under the pyramid of Djoser and is almost aligned with its summit. This shaft is ≈28 m deep and has a square shape with 7 m sides. Its bottom part widens to ≈10 m on the last, deepest 6 m, forming a chamber ( Fig 12 and S6 Fig in S2 File ). On its upper part, the shaft extends above the ground level by at least four meters inside the Step Pyramid in the shape of a hemispherical vault that was recently reinforced ( Fig 11 , inset 5 ). This upper part inside the pyramid body remains unexplored. However, as noticed by Lauer, the shaft sides above ground level display comparable masonry to that of the southern shaft, indicating a possible upward extension [ 3 ]. On the pyramid’s north side, a steep trench with stairs provides access to the shaft.

a.: Granite box of Djoser’s complex north shaft serving as an opening-closing system for the water flow coming from side tunnels -source: [ 113 ]. b.: Limestone piles supporting the box - source: [ 3 ]. c: Diagram of the North Shaft plug system. Redrawn from Lauer sketches [ 108 ].

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The ‘south shaft’ is located ~200 m south of the north shaft, close to the Deep Trench ( Fig 11 , inset 1 ). Its dimensions and internal layout are broadly similar to the north shaft’s. The substructure of the south shaft is entered through a west-facing tunnel-like corridor with a staircase that descends about 30 m before opening up inside the shaft. The staircase then continues east and leads to a network of galleries whose layout imitates the blue chambers below the Step Pyramid. As mentioned earlier, a 200 m-long tunnel connects the lower part of the north and south shafts ( Fig 11 , orange pipe). A series of deep niches located on the south face of the south shaft [ 97 ], the shape of which resembles that of the Deep Trench’s compartments 1 and 2, might indicate a former connection between both. This point remains to be confirmed by additional investigation.

The south shaft is connected to a rectangular shaft to the west via a tunnel-like corridor with a staircase that descends approximately 30 meters before opening up into the south shaft ( Fig 11 , inset 2 ). At the corridor level, a chamber has been cut into the bedrock parallel to the descending passage [ 3 ], towards the south. This chamber features several incompletely excavated niches on its south wall, which could extend under the south wall of the Djoser complex ( Fig 8 ). Pending further excavations, they might indicate a connection with the Deep Trench.

4.3 The twin shafts’ internal layout: two plug-systems topped with maneuvering chambers

The initial purpose of the twin shafts’ granite boxes has been largely debated [ 15 , 100 ]. The presence of two shafts with two similar granite boxes and almost identical substructures was previously explained as a separation of the body and spirit of Djoser [ 100 ]. However, the Pharaoh’s body is actually missing and was not found during modern excavations. Several authors and explorers excluded the possibility of King Djoser’s burial in the north shaft [ 15 , 103 ]. Vyse claimed [ 15 ] that the box’s internal volume was too narrow for moving a coffin without breaking the body. Firth and Quibell considered [ 103 ] the fragments found by Gunn and Lauer [ 104 ] to be of mummies of ‘late date’, possibly belonging to the Middle or New Kingdom. Finally, a thorough radiocarbon dating [ 105 ] on almost all retrieved remains [ 104 , 106 , 107 ] located near the granite box excluded the possibility that ‘ even a single one of them ’[ 105 ] could have belonged to King Djoser. Therefore, although the northern shaft had clear funerary significance much later, its original purpose during the time of Djoser may have been different.

Unfortunately, the main part of the materials that filled the twin shafts was removed during past archaeological excavations, mainly in the 1930s [ 108 ], leaving only the two granite boxes at their bottom ( Fig 11 , insets 3 and 4 ). Therefore, the shafts’ internal layout description is mainly based on the explorers’ archaeological reports and testimonies[ 109 – 111 ].

The two granite boxes are broadly similar in shape and dimensions. Both are made of four layers of granite blocks and present top orifices closed by plugs that weigh several tons ( Fig 12A ). The southern box is slightly smaller, with a plug made of several pieces, making it less versatile. The north box does not lay directly on the underlying bedrock but is perched on several piles of limestone blocks supporting the lower granite beams ( Fig 12B ), tentatively attributed to robbers by Lauer [ 3 ]. The space around the box is connected with four tunnels arranged perpendicularly on each side of the shaft (see Supplement ). This space was filled with several successive layers [ 108 ] ( Fig 12C , grey parts). The lowermost layer consisted of coarse fragments of limestone waste and alabaster, making it permeable. Meanwhile, the upper layer, going up to the box ceiling’s level, was made of limestone jointed with clay mortar [ 108 ], i . e ., less permeable [ 112 ]. This ceiling was itself covered by a 1.50 m thick layer of alabaster and limestone fragments plus overlying filling ( Fig 12C , blue part), except around the plug hole, which was encircled by a diorite lining, a particularly solid rock ( Fig 12C , green part).

Directly above the granite boxes were ‘maneuvering chambers [ 108 ]’ that enabled the plug to be lifted. The plug closing the north shaft’s box has four vertical side grooves, 15 cm in diameter, intended for lifting ropes ( Fig 12C ) and a horizontal one, possibly for sealing. Below the chamber ceiling and just above the orifice, an unsheathed wooden beam was anchored in the east and west walls ( Fig 12C ). This beam likely supported ropes to lift the plug, similar to those found in the south shaft with friction traces [ 108 ].

Interestingly, the granite stones forming the granite box ceiling were bounded by mortar ( Fig 12A ), creating an impermeable barrier with the shaft’s lower part and leaving the plug’s hole as the only possible connection between the shaft and the inside of the box. Conversely, most joints between the box’s side and bottom stones, connected with the permeable bottom layer, were free from mortar.

These details, thoroughly documented during Lauer’s excavation [ 3 , 108 ] and visible on pictures ( Fig 12A and 12B ), clearly point to technical rather than symbolic application. Taken together, the granite box’s architecture and its removable plug surrounded by limestone clay-bound blocks present the technical signature of a water outlet mechanism.

When opened, such a plug system would have allowed the north shaft to be filled with water from the Deep Trench or, in another scenario, from the Dry Moat’s eastern section. The permeable surrounding filling would have permitted water discharge control from the four side tunnels. Then, the water could only seep through the granite box’s lower joints. This design would have prevented water from rushing through the system at high speed and with pressure shocks.

Considering water coming from the Deep Trench (elevation delta: 10–20 m), the retaining walls and the many layers’ cumulated weight stacked over the granite box acted as a lateral blockage and would have prevented the box ceiling from being lifted due to the underlying water pressure.

4.4 Consistency of the internal architecture of the Djoser’s complex with a hydraulic lift mechanism

After gathering all the elements of this study, we deduce that the northern shaft’s layout is consistent with a hydraulic lift mechanism to transport materials and build the pyramid. Elements at our disposal indicate that the south and north shafts could be filled with water from the Dry Moat. A massive float inside the north shaft could then raise stones, allowing the pyramid’s construction from its center in a ‘volcano’ fashion ( Fig 13 ).

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Although a connection between the Compartment -2 and the Djoser shafts has yet to be identified, it is highly probable that sediment-free water from the Deep Trench was used in this system ( Fig 13 , disk ‘ 1 ’). This water quality would have reduced the risk of fouling and malfunction because it minimizes the presence of sand and clay that feed into the north shaft. This would prevent the deposition and progressive filling in the tunnels and connections, as well as the clogging of the joints between the bottom and side granite blocks of the box. The 200 m-long underground pipe [ 91 ] that connects the north and south shafts is then consistent with the transfer of water from the Deep Trench’s water treatment system to the north shaft, possibly via the south shaft.

Furthermore, there is a proven connection between the tunnels surrounding the north shaft and the Dry Moat through the Deslandes’ pipes [ 91 ] on the eastern side of the complex ( Figs 11 and 13 ). Pending further investigation, we hypothesize that the water inlet was located to the south ( Fig 13 , disk ‘ 1 ’), with the outlet(s) sending water toward the east through two juxtaposed pipes (disk ‘ 2 ’). Several horizontal galleries connected to these two pipes were acacia-cased [ 3 ], a technique commonly used to safeguard the walls in hydraulic works in ancient Egypt. A large stone portcullis [ 108 ] found in one of these galleries may have served as a versatile gate closed during the water filling of the north shaft.

In another scenario, the Deslandes’ juxtaposed pipes ( Fig 13 , disk ‘ 2 ’) could be considered as a water inlet for unfiltered water.

Finally, we hypothesize that a hydraulic lift, a massive float that was possibly made of wood and weighed several tons (see Supplement ), should run slowly inside the shaft to prevent instabilities and friction with the sides. The stones could have been elevated by filling and emptying cycles, allowing the lift to move up and down with stones ( Fig 13 ). These stones could have passed along the northern entrance until the central shaft. Recent discoveries have shown that this gallery was kept open until the very end of the pyramid’s construction, after which it was closed [ 1 , 91 ]. In our scenario, the stones could have been transported directly at ground level, corresponding to the pyramid’s first course, or slightly higher through a ramp penetrating in a (currently sealed) corridor some meters above the ground level. This configuration would have had the particular advantage of minimizing the elevation gain for which the hydraulic lift would be required. The stones could have been transported via the so-called ‘Saite gallery [ 114 ]’ in a final scenario. Although Firth [ 114 ] considers this gallery to postdate the III rd Dynasty, it remains possible that it was recut on the basis of an earlier gallery.

4.5 Modelling the hydraulic lift mechanism

We developed a simple numerical model of the hydraulic lift to study its water consumption and loading capacity (see Supplement ). The model was kept as simple as possible to be easily checked and only intended to give relevant orders of magnitudes.

The hydraulic lift is modelled as a float loaded with stones to build the pyramid and with a vertical extension to raise this material at the necessary level. Based on the initial altitude of the lift, Z m , which cannot be below 17m from ground level (the bottom of the shaft was filled with the box and overlying rocks, see Fig 12C ), and assuming a loading of the material on the lift at the ground level, the maximum height that can be reached in one cycle is <17m. To achieve greater heights, we hypothesize that the lift platform was blocked during the float descent, e . g ., using beams (see Fig 14 ). This modification would have allowed the platform to reach higher altitudes by adding or unfolding an extension. For the top of the pyramid, the float could be conversely used as a counterweight when descending, pulling on ropes that would haul the platform after passing over pulleys above the shaft head. A dual-use method involving hauling during shaft draining and elevating during water filling would have been the optimal management approach.

The lift platform (red line), and extension support (orange line) during the unfolding of the lower element are represented. The associated holes are to be localized in further excavation of the upper part of the shaft.

https://doi.org/10.1371/journal.pone.0306690.g014

The beginning of the pyramid building was most probably performed using ramps prolonging the path from the local quarry, possibly the Dry Moat [ 44 ]. To provide an upper bound of water consumption, we modelled the pyramid building using the hydraulic lift from the first layer at ground level. Our model suggests that this upper bound value is 18 Mm 3 of water required to build the whole pyramid using the float to lift stones only when the shaft is filled (see Supplement ). A few million were required to build the first 20 m and could be saved if ramps were used instead. The total amount of water needed would have been reduced by about one-third if the float had been used as a counterweight, pulling on ropes to haul stones on a platform suspended in the top part of the shaft rather than being located on a wooden frame extension attached to the float. Finally, if both lifting (when filling the shaft) and hauling (when draining the shaft) were used, the water consumption would decrease by two-thirds. If the loading was not performed at ground level but rather through a ramp and gallery above ground level, about one-quarter of the water would be saved if, for instance, using a 5 m-high ramp and 43% for a 10 m-high ramp. Further investigation above the vault and on the pyramid sides could help to identify such an eventual gallery. If, conversely, the loading was performed about 13 m below ground level in the top part of the northern gallery ( S6 Fig in S2 File ), the water consumption would typically increase by two-thirds.

On the other hand, through our research and calculations, we have determined that the Wadi Taflah catchment had the capacity to supply 4–54 Mm 3 over 20–30 years of construction, therefore not enough when assuming only pessimistic values (lower bound for rainfall and runoff coefficient, fast construction and sub-optimal use of the lift just using it when water rose), but sufficient when assuming intermediate values, and eight-times enough water to meet this demand when assuming optimistic values (upper bounds of parameters and dual lifting-hauling functioning). If further research demonstrates that the higher clay and silt content possibly present at that time shortly after the Green Sahara period probably led to increased runoff coefficients by a factor of 2–3 or even more, the resource would be increased by the same factor.

The climatological conditions on the Saqqara plateau during the III rd Dynasty are still not well understood [ 37 ]. As a first assumption, we estimate that the water supply may have been continuous even without an upper Abusir lake’s permanent existence, thanks to the flow from the wadi Abusir and, more significantly, through a probable derivation system from the nearby Wadi Taflah, assuming this large catchment had a more perennial runoff regime. Pedological investigations would be worthwhile in the plateau area and in the talweg of both wadis to look for evidence of more frequent water flow.

As a result, the hydraulic mechanism may have only been usable when sufficient water supply was available, so it may have only been used periodically. Other techniques, such as ramps and levees, were likely used to bring the stones from the quarries and adjust their positions around the lifting mechanism or when it was not in operation.

5. Discussion

A unified hydraulic system.

Based on a transdisciplinary analysis, this study provides for the first time an explanation of the function and building process of several colossal structures found at the Saqqara site. It is unique in that it aligns with the research results previously published in the scientific literature in several research areas: hydrology, geology, geotechnics, geophysics, and archaeology. In summary, the results show that the Gisr el-Mudir enclosure has the feature of a check dam intended to trap sediment and water, while the Deep Trench combines the technical requirements of a water treatment facility to remove sediments and turbidity. Together, these two structures form a unified hydraulic system that enhances water purity and regulates flow for practical uses and vital needs. Among the possible uses, our analysis shows that this sediment-free water could be used to build the pyramid by a hydraulic elevator system.

By its scale and level of engineering, this work is so significant that it seems beyond just building the Step Pyramid. The architects’ geographical choices reflect their foresight in meeting various civil needs, making the Saqqara site suitable for settling down and engaging in sedentary activities, such as agriculture, with access to water resources and shelter from extreme weather conditions. This included ensuring adequate water quality and quantity for both consumption and irrigation purposes and for transportation, navigation, or construction. Additionally, after its construction, the moat may have represented a major defensive asset, particularly if filled with water, ensuring the security of the Saqqara complex [ 115 ].

The hydraulic lift mechanism seems to be revolutionary for building stone structures and finds no parallel in our civilization. This technology showcases excellent energy management and efficient logistics, which may have provided significant construction opportunities while reducing the need for human labor. Furthermore, it raises the question of whether the other Old Kingdom pyramids, besides the Step Pyramid, were constructed using similar, potentially upgraded processes, a point deserving further investigation.

Overall, the hydraulic lift could have been a complementary construction technique to those in the literature for the Old Kingdom [ 8 , 10 ]. Indeed, it is unlikely that a single, exclusive building technique was used by the ancient architects but that a variety of methods were employed in order to adapt to the various constraints or unforeseen circumstances of a civil engineering site, such as a dry spell. Therefore, the beginning of the pyramid building was most probably performed using ramps prolonging the path from the local quarry. According to petrographic studies [ 47 ], the main limestone quarry of the Saqqara site could correspond to the Dry Moat that encircles the Djoser Complex, providing access on the four sides of the pyramid for the extracted blocks and reducing the average length of the ramps.

An advanced technical and technological level

By their technical level and sheer scale, the Saqqara engineering projects are truly impressive. When considering the technical implications of constructing a dam, water treatment facility, and lift, it is clear that such work results from a long-standing technical tradition. Beyond the technical aspects, it reflects modernity through the interactions between various professions and expertise. Even though basic knowledge in the hydraulics field existed during the early Dynastic period, this work seems to exceed the technical accomplishments mentioned in the literature of that time, like the Foggaras or smaller dams. Moreover, the designs of these technologies, such as the Gisr el-Mudir check-dam, indicate that well-considered choices were made in anticipation of their construction. They suggest that the ancient architects had some empirical and theoretical understanding of the phenomena occurring within these structures.

…questioning the historical line

The level of technological advancement displayed in Saqqara also raises questions about its place in history. When these structures were built remains the priority question to answer . Were all the observed technologies developed during the time of Djoser, or were they present even earlier? Without absolute dating of these works, it is essential to approach their attribution and construction period with caution. Because of the significant range of techniques used to build the Gisr el-Mudir, Reader estimates [ 70 ] that the enclosure may have been a long-term project developed and maintained over several subsequent reigns, a point also supported by the current authors. The water treatment facility follows a similar pattern, with the neatly cut stones being covered and filled with rougher later masonry. Finally, the Djoser Step Pyramid also presents a superposition of perfectly cut stones, sometimes arranged without joints with great precision and covered by other rougher and angular stones [ 3 ]. Some of these elements led some authors [ 6 , 100 ] to claim that Djoser’s pyramid had reused a pre-existing structure.

Some remaining questions

The Deep Trench was intentionally sealed off at some point in history, as evidenced by the pipe blockage between Compartment-0 and Compartment-1. The reasons are unknown and speculative, ranging from a desire to construct buildings (such as the Khenut, Nebet, or Kairer mastabas) above the trench to a technical malfunction or shutdown due to a water shortage. This sealing might also have been done for other cultural or religious purposes.

The current topography of the land around the Djoser complex, although uncertain given the natural or anthropogenic changes that have occurred over the last five millennia, does not support the existence of a trench to the east side. Therefore, our observations join those of Welc et al. [ 61 ] and some of the first explorers [ 63 ], reasonably attributing only three sections to the Dry Moat.

6 Materials and methods

• High-resolution commercial satellite images (Airbus PLEIADES, 50 cm resolution) and digital elevation models (DEM) were computed and analyzed to identify Abusir wadi’s palaeohydrological network impact on Djoser’s construction project. The processing sequence to generate DEM was mainly achieved using the Micmac software [ 116 ] developed by the French National Geographic Institute (IGN) and the open-source cross-platform geographic information system QGIS 3 . 24 . 3 . Tisler .
• Geospatial data analysis was performed using the open-source WebGL-based point cloud renderer Potree 1.8.1 and QGIS 3 . 24 . 3 . Tisler .
• The 2D CAD profiles of the Step Pyramid Complex presented throughout this article were produced using Solidworks 2020 SP5 (Dassault Systems) , Sketchup Pro 2021 (Trimble) , Blender (Blender Foundation) , and Unreal Engine 5 (Epic Games) , mainly based on dimensions collected by successive archaeological missions during the last two centuries reported in the literature.
• The Wadi Taflah watershed and the catchment area west of Gisr el-Mudir have been identified and characterized using QGIS 3 . 24 . 3 . This was done with the help of the Geomeletitiki Basin Analysis Toolbox plugin, developed by Lymperis Efstathios for Geomeletitiki Consulting Engineers S . A . based in Greece.
• The modeling of the hydraulic lift mechanism was performed using the open-source programming software RStudio 2022 . 07 . 2 .

7. Concluding remarks and perspectives

This article discloses several discoveries related to the construction of the Djoser complex, never reported before:

• The authors presented evidence suggesting that the Saqqara site and the Step Pyramid complex have been built downstream of a watershed. This watershed, located west of the Gisr el-Mudir enclosure, drains a total area of about 15 km 2 . It is probable that this basin was connected to a larger one with an estimated area of approximately 400 km 2 . This larger basin once formed the Bahr Bela Ma River , also known as Wadi Taflah , a Nile tributary.
• Thorough technical analysis demonstrates that the Gisr el-Mudir enclosure seems to be a massive sediment trap (360 m x 620 m, with a wall thickness of ~15 m, 2 km long) featuring an open check dam. Given its advanced geotechnical design, we estimate that such work results from a technical tradition that largely predates this dam construction. To gain an accurate understanding of the dam’s operating period, the current authors consider it a top priority to conduct geological sampling and analysis both inside and outside the sediment trap. This process would also provide valuable information about the chronological construction sequence of the main structures found on the Saqqara plateau.
• The hydrological and topographical analysis of the dam’s downstream area reveals the potential presence of a dried-up, likely ephemeral lake, which we call Upper Abusir Lake, located west of the Djoser complex. The findings suggest a possible link between this lake and the Unas hydrological corridor, as well as with the ‘Dry Moat’ surrounding the Djoser complex.
• The ‘Dry Moat’ surrounding the Djoser complex is likely to have been filled with water from the Upper Abusir Lake, making it suitable for navigation and material transportation. Our first topographical analysis attributes only three sections to this moat (West, North, and South).
• The Dry Moat’s inner south section is located within the Unas hydrological corridor. The linear rock-cut structure built inside this area, called ‘Deep Trench,’ consisting of successive compartments connected by a rock conduit, combines the technical requirements of a water treatment system: a settling basin, a retention basin, and a purification system.
• Taken as a whole, the Gisr el-Mudir and the Deep Trench form a unified hydraulic system that enhances water purity and regulates flow for practical uses and vital needs.
• We have uncovered a possible explanation for how the pyramids were built involving hydraulic force. The internal architecture of the Step Pyramid is consistent with a hydraulic elevation device never reported before. The current authors hypothesize that the ancient architects could have raised the stones from inside the pyramid, in a volcano fashion. The granite stone boxes at the bottom of the north and south shafts above the Step Pyramid, previously considered as two Djoser’s graves, have the technical signature of an inlet/outlet system for water flow ( Fig 15 ). A simple modeling of the mechanical system was developed to study its water consumption and loading capacity. Considering the estimated water resources of the Wadi Taflah catchment area during the Old Kingdom, the results indicate orders of magnitude consistent with the construction needs for the Step Pyramid.

Graphical conclusion

North Saqqara map showing the relation between the Abusir water course and the Step Pyramid construction process (Inset). The arrows figuring the flow directions are approximate and given for illustrative purposes based on the Franco-Egyptian SFS/IGN survey [ 52 ]. Satellite image: Airbus Pléiades, 2021-07-02, reprinted from Airbus D&S SAS library under a CC BY license, with permission from Michael Chemouny, original copyright 2021.

https://doi.org/10.1371/journal.pone.0306690.g015

Supporting information

https://doi.org/10.1371/journal.pone.0306690.s001

https://doi.org/10.1371/journal.pone.0306690.s002

https://doi.org/10.1371/journal.pone.0306690.s003

Welcome to 2024! Happy New Year!

Research Writing ~ How to Write a Research Paper

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Papers should have a beginning, a middle, and an end. Your introductory paragraph should grab the reader's attention, state your main idea and how you will support it. The body of the paper should expand on what you have stated in the introduction. Finally, the conclusion restates the paper's thesis and should explain what you have learned, giving a wrap up of your main ideas.   

1. The Title The title should be specific and indicate the theme of the research and what ideas it addresses. Use keywords that help explain your paper's topic to the reader. Try to avoid  abbreviations  and  jargon.  Think about keywords that people would use to search for your paper and include them in your title. 

2. The Abstract The abstract is used by readers to get a quick overview of your paper. Typically, they are about 200 words in length (120 words minimum to  250 words maximum). The abstract should introduce the topic and thesis, and should provide a general statement about what you have found in your research. The abstract allows you to mention each major aspect of you topic and helps readers decide whether they want to read the rest of the paper. Because it is a summary of the entire research paper, it is often written last. 

3. The Introduction The introduction should be designed to attract the reader's attention and explain the focus of the research. You will introduce your overview of the topic, your main points of information, and why this subject is important. You can introduce the current understanding and background information about the topic. Toward the end of the introduction, you add your thesis statement, and explain how you will provide information to support your research questions. This provides the purpose, focus, and structure for the rest of the paper.

4. Thesis Statement Most papers will have a thesis statement or main idea and supporting facts/ideas/arguments. State your main idea (something of interest or something to be proven or argued for or against) as your thesis statement, and then provide  supporting facts and arguments. A thesis statement is a declarative sentence that asserts the position a paper will be taking. It also points toward the paper's development. This statement should be both specific and arguable. Generally, the thesis statement will be placed at the end of the first paragraph of your paper. The remainder of your paper will support this thesis.

Students often learn to write a thesis as a first step in the writing process, but often, after research, a writers viewpoint may change. Therefore a thesis statement may be one of the final steps in writing. 

Examples of thesis statements from Purdue OWL. . .

5. The Literature Review The purpose of the literature review is to describe past important research and how it specifically relates to the research thesis. It should be a synthesis of the previous literature and the new idea being researched. The review should examine the major theories related to the topic to date and their contributors. It should include all relevant findings from credible sources, such as academic books and peer-reviewed journal articles. You will want  to:

• Explain how the literature helps the researcher understand the topic.
• Try to show connections and any disparities between the literature.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.

More about writing a literature review. . .  from The Writing Center at UNC-Chapel Hill More about summarizing. . . from the Center for Writing Studies at the University of Illinois-Urbana Champaign

6. The Discussion ​The purpose of the discussion is to interpret and describe what you have learned from your research. Make the reader understand why your topic is important. The discussion should always demonstrate what you have learned from your readings (and viewings) and how that learning has made the topic evolve, especially from the short description of main points in the introduction. Explain any new understanding or insights you have had after reading your articles and/or books. Paragraphs should use transitioning sentences to develop how one paragraph idea leads to the next. The discussion will always connect to the introduction, your thesis statement, and the literature you reviewed, but it does not simply repeat or rearrange the introduction. You want to: 

• Demonstrate critical thinking, not just reporting back facts that you gathered.
• If possible, tell how the topic has evolved over the past and give it's implications for the future.
• Fully explain your main ideas with supporting information.
• Explain why your thesis is correct giving arguments to counter points.

​7. The Conclusion A concluding paragraph is a brief summary of your main ideas and restates the paper's main thesis, giving the reader the sense that the stated goal of the paper has been accomplished. What have you learned by doing this research that you didn't know before? What conclusions have you drawn? You may also want to suggest further areas of study, improvement of research possibilities, etc. to demonstrate your critical thinking regarding your research.

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• DOI: 10.3724/j.issn.1674-4969.20240036
• Corpus ID: 271264307

Research on the promotion of Big Science Project on Modern Industrial System: A Case Study on the Space Environment Simulation and Research Infrastructure from the Perspective of New Quality Productive Forces

• Yijia Wang , Liang Li
• Published in JOURNAL OF ENGINEERING… 1 July 2024
• Engineering, Environmental Science

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What Are Endnotes? | Guide with Examples

Published on March 29, 2022 by Jack Caulfield . Revised on June 7, 2022.

Endnotes are notes that appear at the end of your text in a piece of academic writing. They’re indicated in the text with numbers (or occasionally other symbols). Endnotes are used:

• For citations in certain styles
• To add extra information that doesn’t fit smoothly into the main text

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Endnotes vs. footnotes, how to use endnotes, endnotes in chicago style, endnotes in apa style, endnotes in mla style, how to insert endnotes in word, frequently asked questions about footnotes and endnotes.

Endnotes are sometimes confused with footnotes . Footnotes are also used to provide citations and/or supplementary information, but they appear at the bottom of the relevant page instead of all together at the end.

• Clutter your writing less than footnotes, since they’re all grouped together instead of spread throughout the text
• Are less convenient, since the reader has to flip to the back to read the notes
• Are convenient, since the reader finds the additional information on the same page as the relevant part of the text
• Can make your text appear messy, especially if there are a lot of them

You should usually choose either footnotes or endnotes and use them consistently. Your instructor may tell you which style of note to use.

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Endnote numbers appear at the end of the clause or sentence the endnote relates to. The number appears after any punctuation, unless the clause ends with an em dash, in which case it appears before it. There’s no space added after the number.

The general consensus now—though there are dissenting voices 1 —is that this experiment was simply too methodologically flawed to produce valid results. 2

Endnotes are numbered consecutively in the order they appear in your text. Each note has a unique number; don’t repeat the same number even if you cite the same source more than once.

In Chicago notes and bibliography style , you use endnotes (or footnotes) for citations. Either kind of note can also be used to add extra information: further examples, commentary on the sources you cite, or more detailed discussion of ideas you mention in the text.

Place your Chicago endnotes at the end of the relevant clause or sentence. A citation endnote provides full information about a source the first time you cite it, and shortened information for any further citations of that source.

                    1. Hanna Pickard, “What Is Personality Disorder?” Philosophy, Psychiatry, & Psychology 18, no. 3 (September 2011): 182. https://doi.org/10.1353/ppp.2011.0040.

          2. Pickard, “What Is Personality Disorder?” 182.

You should still include a full list of your sources in a bibliography after the endnotes, unless you’re writing a very short paper and have been told you don’t need to.

The endnotes page appears just before the bibliography and starts with the title “Notes” written in bold and centered. The notes themselves are formatted as follows:

• Leave a blank line between endnotes, and single-space the notes themselves.
• Indent the start of each endnote.
• Write the note numbers in normal text, not superscript, followed by a period and then a space.

Either endnotes or footnotes may be used in APA Style to provide additional information. They’re not used for citation; for that you’ll use APA in-text citations instead.

APA endnotes are used to provide copyright attributions where necessary. They can also be used, for example, to elaborate on ideas in the text or provide further examples. Do this sparingly, however; APA cautions against adding unnecessary details.

1 Copyright 2022 by Scribbr. Reprinted with permission.

        2 Admittedly, the issue is not as straightforward as this brief summary suggests. See Prakash (2019) for a more in-depth consideration of …

Endnotes appear on a separate page after the reference list , with the heading “Footnotes” (confusingly, APA doesn’t use the term “endnotes”) in bold and centered at the top.

The notes are written as double-spaced indented paragraphs. Start each note with its number, in superscript and followed by a space.

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MLA in-text citations appear in parentheses in the text, but you can use endnotes to avoid cluttering the text if you need a lot of citations in one place.

MLA endnotes may also be used to provide additional information—any necessary clarifications, further examples, or expansions of ideas covered briefly in the text.

      1 See James 35; Lanning 15–25; and Johnson 77.

       2 Other nations, including Italy and France, were undergoing similar political convulsions during the same period.

List your endnotes on a separate page before the Works Cited list, and title them either “Notes” or “Endnotes.” Indent the first line of each endnote, and start the note with the number in superscript followed by a space. Endnotes should be double-spaced.

It’s straightforward to insert endnotes automatically in many word processors, including Microsoft Word. Just follow these steps:

• Click on the point in the text where you want the endnote number to appear.
• Open the “References” tab at the top, and click on “Insert Endnote.”
• Type something in the endnote that appears at the end of your document.

But if you’re following one of the styles covered above, do adjust the formatting to match their requirements and add a heading for the endnotes page.

Footnotes appear at the bottom of the page they refer to. This is convenient for the reader but may cause your text to look cluttered if there are a lot of footnotes.

Endnotes appear all together at the end of the whole text. This may be less convenient for the reader but reduces clutter.

Both footnotes and endnotes are used in the same way: to cite sources or add extra information. You should usually choose one or the other to use in your text, not both.

To insert endnotes in Microsoft Word, follow the steps below:

• Click on the spot in the text where you want the endnote to show up.
• In the “References” tab at the top, select “Insert Endnote.”
• Type whatever text you want into the endnote.

If you need to change the type of notes used in a Word document from footnotes to endnotes , or the other way around, follow these steps:

• Open the “References” tab, and click the arrow in the bottom-right corner of the “Footnotes” section.
• In the pop-up window, click on “Convert…”
• Choose the option you need, and click “OK.”

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