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Research & citation

APA 7, MLA 9 or Chicago 18? How to Cite Sources Correctly (With Examples)

· Research & citation

Citation styles exist so that a reader can find exactly what you read. They look fussy because they are precise, but each one follows a logic, and once you see it you will stop copying formats from random websites. Here are the three styles you are most likely to be asked for, in their current editions: APA 7th edition (2019), MLA 9th edition (2021) and the Chicago Manual of Style, 18th edition (2024).

Which style should you use?

  • APA (American Psychological Association): psychology, education, nursing, social sciences, business. It puts the date up front, because in these fields how recent a study is matters.
  • MLA (Modern Language Association): literature, languages, cultural studies. It foregrounds the author and the page, because you often quote and analyse the exact words.
  • Chicago: history, arts and some humanities, usually with footnotes (the "notes and bibliography" system); an author-date variant exists for the sciences.

The rule that beats all others: use the style and edition your instructor or journal asks for, and use it consistently.

APA 7th edition

In-text: author and year, plus a page number for direct quotations: (Nguyen, 2022) or (Nguyen, 2022, p. 14). Two authors: (Nguyen & Patel, 2022). Three or more: (Nguyen et al., 2022).

Reference list (journal article):
Nguyen, T., & Patel, R. (2022). Sleep and exam performance in first-year students. Journal of Higher Education Research, 14(3), 201–219. https://doi.org/10.xxxx/xxxxx

Book: Author, A. A. (Year). Title of work: Capital letter also for subtitle. Publisher.

Web page: Author or Organization. (Year, Month Day). Title of page. Site Name. URL

The reference list is in alphabetical order, double-spaced, with a hanging indent. The official APA Style examples cover more than a hundred source types.

MLA 9th edition

In-text: author and page, no comma: (Nguyen 14). If you name the author in your sentence, only the page goes in brackets.

Works Cited (journal article):
Nguyen, Thanh, and Ravi Patel. "Sleep and Exam Performance in First-Year Students." Journal of Higher Education Research, vol. 14, no. 3, 2022, pp. 201–19. https://doi.org/10.xxxx/xxxxx.

MLA is built on "core elements" in a fixed order: author, title of source, title of container, other contributors, version, number, publisher, publication date, location. You include the ones that apply. The MLA Style Center explains each element with examples.

Chicago 18th edition (notes and bibliography)

First footnote:
1. Thanh Nguyen and Ravi Patel, "Sleep and Exam Performance in First-Year Students," Journal of Higher Education Research 14, no. 3 (2022): 205.

Shortened note for later citations: 2. Nguyen and Patel, "Sleep and Exam Performance," 207.

Bibliography:
Nguyen, Thanh, and Ravi Patel. "Sleep and Exam Performance in First-Year Students." Journal of Higher Education Research 14, no. 3 (2022): 201–19. https://doi.org/10.xxxx/xxxxx.

The 18th edition, published in September 2024, simplified several rules; if your department still uses the 17th, the differences are small but check the guide it gives you. The Chicago citation quick guide is free online.

Citing websites, videos and AI tools

  • No author? Use the organization as author; if there is none either, start with the title.
  • No date? APA uses "n.d."; MLA leaves the date out and may add an access date.
  • Generative AI. Both APA and MLA have published guidance on citing text produced by tools such as ChatGPT (APA Style blog, April 2023; MLA Style Center, March 2023). Before citing, check whether your course allows these tools at all, and describe how you used them.

Five habits that save hours

  1. Record the full reference the moment you read a source, including the DOI or URL and the page numbers you used.
  2. Use a reference manager (Zotero is free and open source) and still proofread its output: it inherits every error in the database it imported from.
  3. Check capitalisation: APA uses sentence case for article titles, MLA and Chicago use title case.
  4. Prefer the DOI over a database link whenever one exists.
  5. Cite paraphrases too, not only quotations. Using someone's idea in your own words still requires a citation.

Citations are not only about avoiding plagiarism; they are evidence. A well-sourced paragraph is a stronger paragraph, which is why the structure of a good argumentative essay depends on them.

Sources

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