Citations do two jobs: they credit the people whose work you used, and they let your reader find your sources. Different academic fields settled on different ways of doing this. The three styles you’re most likely to meet are APA, MLA and Chicago.
This guide follows the APA Publication Manual, 7th edition (2019); the MLA Handbook, 9th edition (2021); and The Chicago Manual of Style, 18th edition (2024).
At a glance
| APA | MLA | Chicago notes and bibliography | Chicago author-date | |
|---|---|---|---|---|
| Common in | Psychology, education, nursing, social sciences | Literature, languages, humanities | History, arts, some humanities | Sciences and social sciences |
| In-text format | (Author, Year, p. #) | (Author Page) | Numbered footnote or endnote | (Author Year, Page) |
| List at the end | References | Works Cited | Bibliography | References |
| Date position | Right after the author | Near the end | Near the end | Right after the author |
The same book in each style
Here’s how one book — Deep Work, by Cal Newport — appears in each style. In every style, the list at the end is in alphabetical order by author’s last name, and each entry uses a hanging indent.
APA (7th edition)
- In text: (Newport, 2016, p. 45)
- Reference list: Newport, C. (2016). Deep work: Rules for focused success in a distracted world. Grand Central Publishing.
APA uses the author’s initials, puts the year in parentheses right after the name, and uses sentence case for titles: only the first word, the first word after a colon and proper nouns are capitalized.
MLA (9th edition)
- In text: (Newport 45)
- Works Cited: Newport, Cal. Deep Work: Rules for Focused Success in a Distracted World. Grand Central Publishing, 2016.
MLA uses the author’s full name and title case, and puts no comma between the author’s name and the page number in the in-text citation.
Chicago (18th edition), notes and bibliography
- First note: 1. Cal Newport, Deep Work: Rules for Focused Success in a Distracted World (Grand Central Publishing, 2016), 45.
- Later notes: 2. Newport, Deep Work, 45.
- Bibliography: Newport, Cal. Deep Work: Rules for Focused Success in a Distracted World. Grand Central Publishing, 2016.
The note number in your text is a superscript, placed after the punctuation at the end of the clause or sentence.
Chicago (18th edition), author-date
- In text: (Newport 2016, 45)
- Reference list: Newport, Cal. 2016. Deep Work: Rules for Focused Success in a Distracted World. Grand Central Publishing.
Other common sources
Journal articles and websites follow the same patterns, with a few more pieces of information:
- Journal articles need the journal name, volume, issue and page range. If the article has a DOI — a permanent link beginning
https://doi.org/— include it. - Web pages need the site name and URL, and sometimes the date you accessed them. The rules for access dates differ between styles, so check the style guide.
- AI-generated text: APA, MLA and Chicago have all published guidance on citing generative AI tools. Check your course policy first — see our guide to studying with AI chatbots.
Which should you use?
- If your instructor or department specifies a style, use it — including the edition.
- If you’re submitting to a journal, follow its author guidelines, which may use a variation of a standard style.
- If nobody has specified one, ask. If you still have to choose, use the style most common in your field. Above all, be consistent.
Where to check the details
- The official guides: APA Style, the MLA Style Center and The Chicago Manual of Style Online all publish free examples and answers to common questions. The full Chicago manual requires a subscription, which many university libraries provide.
- The Purdue Online Writing Lab at owl.purdue.edu has free guides to all three styles.
- Reference managers such as Zotero format citations for you — see our Zotero beginner’s guide. Always check what they produce.
Frequently asked questions
What is the difference between APA and MLA?
APA, used mostly in psychology, education and the social sciences, puts the year right after the author, as in (Newport, 2016, p. 45). MLA, used mostly in literature and the humanities, emphasizes author and page, as in (Newport 45). APA uses sentence case for titles in its reference list, while MLA uses title case.
Which citation style should I use?
Use the style and edition your instructor or department specifies. If none is specified, ask. Otherwise, use the style most common in your field and apply it consistently.
Do I need to include the city of publication in citations?
Not in the current editions of APA, MLA or Chicago. Older editions asked for the city where a book was published, but the current editions no longer require it.
What is the difference between Chicago notes and bibliography and author-date?
Notes and bibliography, common in history and the arts, uses numbered footnotes or endnotes plus a bibliography. Author-date, common in the sciences and social sciences, uses short in-text citations such as (Newport 2016, 45) plus a reference list.
