APA, MLA, and Chicago citations usually contain the same facts, but they arrange and style them differently. APA emphasizes date, MLA emphasizes the source's container, and Chicago offers two systems. This guide uses Chicago 18 Notes and Bibliography, the system common in history and the humanities. Always use the style and edition assigned by your instructor or publisher.
Book example
| APA 7 | Rivera, A. (2024). Designing useful systems. North Star Press. |
|---|---|
| MLA 9 | Rivera, Ana. Designing Useful Systems. North Star Press, 2024. |
| Chicago 18 N&B | Rivera, Ana. Designing Useful Systems. North Star Press, 2024. |
The examples are fictional so the structure is easy to compare. Notice that current Chicago style does not require a city of publication. Use the title capitalization shown by the source for MLA and Chicago; APA reference titles use sentence case.
Journal article with a DOI
A DOI is a persistent identifier. Present it as a URL, such as https://doi.org/10.xxxx/xxxxx, rather than adding “doi:” before it. APA italicizes the journal name and volume; MLA labels volume and issue; Chicago places the year in parentheses in this journal format. Enter the facts once in the Citation Generator and compare all three outputs.
Missing author or date
Do not invent a person. If an organization clearly takes responsibility, use that organization as the author. If no author can be identified, begin with the title. APA uses “n.d.” when no date is available; MLA and Chicago generally omit the missing date and may add an access date when it helps readers locate changing web content. A page footer's copyright year is not automatically the publication date of the page you are citing.
Reference list versus in-text citation
A bibliography entry is not the citation that appears inside a paragraph. APA commonly uses author and year, such as (Rivera, 2024). MLA commonly uses author and page, such as (Rivera 42). Chicago Notes and Bibliography uses a superscript number pointing to a footnote or endnote; the note's punctuation and order differ from the bibliography entry. For a quotation, record the page or other locator while the source is open.
Multiple authors
Thresholds differ. MLA uses the first author followed by “et al.” for three or more authors. Chicago 18 bibliography entries list up to six authors; for seven or more, list the first three and “et al.” APA 7 lists up to 20 authors in a reference entry, with a special ellipsis rule for 21 or more. Automated output deserves a final comparison with the official examples because unusual creators, editions, translations, databases, and archival sources require extra fields.
Official style guides
- APA Style — reference examples
- MLA Style Center — Works Cited quick guide
- Chicago Manual of Style — citation quick guide
Style information reviewed September 2026.