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Cite Sources


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You’ve probably heard your teacher or professor talk about the importance of including citations in your research papers. But what exactly are citations? Why are they so important, and what are the different types? Read on for citation basics.

Here’s a table of contents for this guide: 

What is a Citation?

To begin, let’s examine what a citation actually is. A citation is how you let your readers know that you used information from outside sources in your work. It also describes those sources, and provides information that allows the reader to track them down. This information could be the author’s name, the publication date, or page numbers. The exact information included in the citation depends on the citation style you are using. Please see the citation manual for your chosen style for more specifics on how to make your citations in that style. Popular styles include MLA formatting, Chicago style, and APA style.

Citation Examples

Why Do We Have Citations?

Having to write citations may seem like another boring step in the paper writing process. However, correctly citing sources in your research projects will ensure that you receive a better grade and create something that uniquely contributes to the subject area you are studying.

It doesn’t matter if you use MLA formatting, APA formatting, or any other citation style. Citing sources is something you should always do.

Here are just a few reasons why it is important for you to cite sources in your work:

Citations Provide Hard Evidence of Your Thesis/Ideas

Citing sources that back up your claim, otherwise known as your thesis statement, creates credibility for you as a researcher. It also opens up room for fact-checking and further research.

  • Bonus points: If you can, find a way to cite a few sources that have the converse opinion or idea, and then demonstrate to the reader why you believe that viewpoint is wrong while backing up your claim up with sources. If you can do this, you are well on their way to winning over the reader to your side.
  • Pro tip: Having many citations from a wide variety of sources related to your thesis indicates to your professor that you are working on a well-researched and respected subject.

Citations Give Credit to the Right People

Citing sources ensures that your reader or teacher can differentiate your original thoughts from the ideas in your sources and of other researchers in your subject area. This ensures that the sources you use receive proper credit for the author’s work, and that as the student, you receive deserved recognition for your unique contributions to the topic. Citations serve as a natural way to place your work within in the broader context of a subject area, and are an easy way for your teacher or professor to gauge your commitment to the project at hand. Going above and beyond in your work is always a good idea!

Citations Promote Originality and Prevent Plagiarism

The point of research projects is not to regurgitate information that can already be found elsewhere. We have Google for that! What your project should aim to do is promote an original idea or put a spin on an existing idea, and use credible sources to promote that idea. Copying or directly referencing a source without proper citations can lead to not only a poor grade, but accusations of academic dishonesty. By backing up your ideas with credible sources, you can easily avoid the trap of plagiarism, and promote further research on their topic. To help people find your unique perspective on your topic and create consistency throughout your work, it is always a good idea to use a specific, standardized citation style, such as APA format or MLA format.

Where Do We Have Citations, and What are the Types of Citations?

Citations typically can be found in two places: at the end of a paper in a bibliography or reference list, and within the text. The latter, sometimes called “in-text” citations, usually consist of a few details about the source, and are generally written in parenthesis at the end of the sentence where you referenced the source.


When Scout meets Boo Radley in To Kill a Mockingbird, she realizes that his reputation does not match his true character (Lee 85).

The citation in the reference list or bibliography corresponds with the in-text citation, and provides more holistic information about the source that you are citing. Publication information is included, as well as a list of all contributors to the source.


Lee, Harper. To Kill a Mockingbird. Perennial Modern Classics, 2006.

Note that each citation style has its own formatting rules regarding in-text and bibliographic citations. An APA citation will have similar information but look different from an MLA citation. Consult the style manual of your chosen citation style for more information.

When Should I Make Citations?

You should make a citation for a source whenever you:

● Directly quote a source
● Paraphrase information from a source
● Use an idea that is expressed in another source
● Make a specific reference to the work of another person

Common Mistakes

Let’s have a moment of silence for anyone out there who just received a graded paper filled with those dreaded red marks. Ugh. Nothing is worse than spending hours and hours pouring your heart and soul into a research paper, only to receive a failing grade or an accusation of plagiarism (gasp!) due to incorrect citations. It’s tough enough finding quality resources, analyzing them, and writing a high quality paper, but to receive marks off for incorrect citing totally crushes the soul.

We know there are so many rules to follow when it comes to citing sources. We’re here to highlight some of the most common citation mistakes students and scholars make when developing their research projects. Check out our top 5 below. Perhaps you’ll recognize a mistake or two you’ve been making in your own work.

If you’re looking for some extra help or guidance, check out the Citation Machine plagiarism and grammar checker. Write your paper, pop it into our “smart proofreader” and watch the magic happen. We’ll provide suggestions for citations and grammar edits so you can worry less about those dreaded red marks and more on your learning. Try it out now!

1. Forgetting to include in-text and parenthetical citations

You’ve found the perfect piece of information to include in your paper. Cool! As you’ve learned throughout school, you need to include a citation for that source in your bibliography or works cited list. Don’t forget to also include an in-text or parenthetical citation in the body of your project.

>Remember, every time outside information is added into a paper, you need to provide the reader with a glimpse as to where that information came from. You can do this with an in-text or parenthetical citation, which includes the author’s name in the sentence or directly after it, in parentheses. Depending on the citation style, you may also need to include the page number or year the source was published.

Here’s an example of how an MLA in-text citation could look in an assignment:

Stockett describes Celia as, “probably ten or fifteen years younger than me, twenty-two, twenty-three, and she’s real pretty” (37).

This excerpt is taken from page 37 in Kathryn Stockett’s book, The Help. In the works cited page at the end of the paper, the reader is provided with a full citation that shares the title of the book, the publisher, the year it was published, and possibly some other key pieces of information, depending on the citation style.

Every piece of information added into a paper needs two citations: a brief one in the body of the project and the full citation on the final page. Bam!

2. Period placement gone wrong

Inside? Outside? Outside and inside? It can be tricky to determine where to place those pesky little periods when including parenthetical citations.

For the majority of citation styles, the period is placed on the outside of the parentheses. Here’s a visual to help you out:

“It’s just that sometimes, our future is dictated by what we are, as opposed to what we want” (Sparks 59).

3. In-text and parenthetical citation overload

If you’re using the same reference over and over in one paragraph, it isn’t necessary to include an in-text or parenthetical citation after each sentence. Instead, save it for the end. The reader will be able to ascertain that all of the information from that single paragraph pertains to the individual in-text or parenthetical citation you’ve included.

4. Using the incorrect citation style or switching between two

Even though there are thousands (yes, thousands!) of citation styles available on Citation Machine, make sure to choose just one style for your project. Not sure whether to choose MLA formatting, APA, Chicago style format or another? Check to see if it’s included in the the assignment’s guidelines. Still not sure? Ask your teacher or school librarian. Whichever style you choose to roll with, make sure it’s consistent throughout the entire project. Remember, citations are included to help readers understand where information originated. If you choose to use various citation styles, it could cause some major confusion.

5. Problems with paraphrasing

A proper paraphrase involves taking someone else’s idea and rewriting it using your own words, in your own writing style. What it’s not is taking someone else’s idea and replacing the words with synonyms. Don’t be a synonym swapper. That’s plagiarism!

If you’re having a tough time trying to paraphrase another author’s words, try this out: Carefully read the text again. When you’re through, put it to the side, and think about what you just read. What was the author’s message? Now, rewrite it, using your own words and writing style. Remember to add an in-text or parenthetical citation at the end of the paraphrase and include the full citation in the works cited or reference page.

5 Tips for Making the Perfect Citation

When you’re in a rush to meet a deadline and hand in your paper ASAP, it can be all too easy to make a mistake that can cost you big time. Citations are an often-overlooked component of a research paper that, when done correctly, can help you get your best grade yet. So how can you be sure that your citations are helping you achieve success? Here are some tips to take your research paper to the next level.

1. Include In-text or Parenthetical Citations When Paraphrasing

It can be tempting to just re-write a sentence from a source to include in your paper. But neglecting inclusion of a parenthetical, or in-text citation can lead to accusations of plagiarism. Being accused of committing plagiarism can not only impact your grade, but can put your enrollment in jeopardy as well. To avoid making this error, be sure to paraphrase carefully, and include a parenthetical or in-text citation in your paper each time you reference an outside source.

2. Periods (Almost) Always Go After the Parenthesis

Something as minor as an incorrectly placed period after a reference can lead to losing major points on your paper. In nearly every citation style with parenthetical citations, the period comes after the parenthesis, not before. Here is an example of a correctly placed period after a reference in APA format:

(Smith, 2005).

3. Be Consistent with Your Citation Style

Some classes require you use MLA format, while others require APA, while still others require Chicago Manual of Style. These specifications can be difficult to keep track of, but being consistent with your style is perhaps the easiest thing you can do to make sure you have well written citations. Double-checking your citations at the end of your paper before handing it in can lead to good last minute improvements.

4. All In-text and Parenthetical Citations Should Correspond with a Reference List Entry

In-text and parenthetical citations can be done while you are writing your paper, and are included each time you include information from an outside source. It is important to remember, however, that each time you do this, you should bear in mind that at the end of your paper in the works cited, bibliography, reference list, etc., there should be a corresponding longer reference to that same source that matches the in-text or parenthetical reference. When you are finished making your in-text and parenthetical references, use them to make a list of full citations you will need to include at the end of your paper.

5. Cite Properly, Not in Excess

While it is important to include citations in your paper, you shouldn’t be including them after each and every sentence you write. The important thing to remember is to cite only if you are including information from an outside source. This information should only be included if you feel that it backs up your claim effectively enough to the point where another researcher could potentially find that source and identify it as being related to your argument. If all the information in one paragraph you write refers to the same source, you only need to include one in-text or parenthetical citation in that paragraph, not after each individual sentence.


Solution #1: Identifying where to place a period in an in-text citation

1. If the in-text citation is at the end of the sentence or quotation, place a period after the citation (outside the parenthesis).

APA examples:

The results of Singh’s (2021) experiment were inconclusive (p. 42).

“The origin of the two variables could not be determined” (Singh, 2021, p. 42).

MLA examples:

The results of Singh’s experiment were inconclusive (42).

“The origin of the two variables could not be determined” (Singh 42).

2. Always use periods after the phrase “et al.”.

APA examples:

As Gregory Cheffsworth, et al. (2021) suggest, “sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store” (p. 12).


“Sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store” (Cheffsworth et al., 2021, p. 12).

MLA examples:

As Gregory Cheffsworth, et al. suggest, “sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store” (p. 12).


“Sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store” (Cheffsworth et al. 12).

3. Block quotations in APA and MLA place the citation after the period.

A block quotation in APA is a quotation that is longer than forty words. The entire block quotations are indented by 0.5-inches.

APA examples:

            I wanted to make a casserole, but I soon realized that I did not have milk. However, as Gregory Cheffsworth, et al. (2021) suggest,

“Sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store but, when one encounters this situation, they must be prepared to adapt to the differences in flavor profiles by incorporating new spices.” (p. 12)

In MLA, if the quotation is longer than four lines, use a block quotation by indenting the entire paragraph 0.5-inches.

MLA example:

            I wanted to make a casserole, but I soon realized that I did not have milk. However, as Gregory Cheffsworth, et al. suggest,

Sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store but, when one encounters this situation, they must be prepared to adapt to the differences in flavor profiles by incorporating new spices. Depending on the selections, the sour cream’s natural taste can be emphasized or completely neutralized. As a result, one should not be afraid of the “sour” in sour cream. (12)

Solution #2: How to choose which citation style to use

  1. First, consult your syllabus, rubric, or writing guidelines. Most often, the expected citation style will be listed. If it is not, ask your teacher or the publication if they have a style preference.
  2. If no preference is given, identify the subject or discipline you are writing in and learn what citation style is usually used (a librarian can help if you’re unsure).
    • Use MLA style if you are writing within the humanities. This includes English literature, language, history, religion, and the arts.
    • Use APA style if you are writing on the sciences, which includes subjects such as geology, education, or psychology.
    • Use Chicago style if you are writing for business, history, or the fine arts.
  3. Note that some scientific genres require their own specific citation guide outside of these three widely used guides. For example, computer science frequently uses the IEEE citation guide.
  4. Look at sample papers or journal articles to see what is typically used.
  5. If all else fails, go to a library or your school’s writing center and ask for help.

Solution #3 When and how to create a direct quote versus a paraphrased citation

  1. Direct quotes list exactly what the source says in quotation marks.
    1. Use a direct quote if the original word structure is meaningful to you or your paper.
      • For example, if you chose to directly quote information because the wittiness of an original excerpt is meaningful to your paper and is altered as a paraphrase.
    2. Avoid using small chunks of direct quotes that do not add meaning to the overall message.
      • For example, when the quoted material is short compared to the rest of the sentence and does not add a significant amount of information. Use a paraphrase instead.
    3. Be aware that writing a direct quote without explaining it or further relating it to your topic can give the impression that you do not understand the information and are simply regurgitating the information.
    4. Avoid overusing direct quotes. Ideally, a paper is mostly written using your own words and thoughts.
  2. A paraphrase is a restatement of what a source said but in your own words. This still needs to be cited since it is not your own original idea.
    • Use a paraphrase if you truly understand the idea/information and you can effectively relay the message in your own words.
    • A paraphrase is also useful if you’re trying to synthesize a long quote or passage into a shorter passage.
    • Before or after the paraphrase, you will need to discuss the information’s significance to your argument or paper.
    • If you find that your paragraph is following the same word structure as the original statement, consider using a direct quote or consider rephrasing the sentence.
    • One more reminder: Include an in-text citation to indicate that the original idea comes from another source.

Example of a direct quote:

            I wanted to make a casserole, but I soon realized that I did not have milk. However, as Gregory Cheffsworth (2021) suggests, “sour cream can be used as a milk substitute whenever one is low on ingredients and willingness to go to the store” (p. 47).

Example of a paraphrased citation:

            I wanted to make a casserole, but I soon realized that I did not have milk. However, I may be able to use sour cream instead of milk (Cheffsworth, 2021).

Finished with your citations and paper? Check out Citation Machine’s handy paper checker! It can help you spot errors and polish your paper. There’s also a free grammar guides library where you can learn what is a verb, an adjective definition, relative pronoun examples, and other grammar-related topics.

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