12 common citation mistakes and how to fix them

Most citation errors fall into a small number of categories. The same dozen mistakes appear over and over in the marking notes published by writing centres at institutions including Purdue OWL, the University of Manchester, and the University of Oxford. Fixing them takes very little time once you know what to look for. This guide is ordered roughly by frequency, with the most common mistakes first.

1. Missing DOIs on journal articles

APA 7, MLA 9, Harvard, and Chicago all want a DOI on every journal article that has one. The DOI is a permanent identifier that survives publisher changes and URL redesigns. Skipping it because the article also has a publisher URL is the single most common reference-list error.

The fix takes thirty seconds. Search the article title on doi.crossref.org or paste it into the CrossRef free DOI lookup. If a DOI exists, it will appear; copy it and format it as a full URL starting with https://doi.org/. If no DOI exists (some humanities journals and older articles), the URL is acceptable in its place.

2. Wrong author order in multi-author works

The author order on the title page of a journal article reflects the contribution hierarchy, and that order is part of the citation. Writers who paste author names from a database without checking sometimes alphabetise them or reorder them by familiarity. This changes who appears in the in-text "et al." citation and misrepresents the paper.

Always copy the author order from the article PDF itself, not from a secondary listing. The reference list entry should match the published paper exactly, including any "and" or comma punctuation between the final two names.

3. Mixing citation styles within one paper

Mixed styles look like a moment of inattention to a marker. The most common mix-up is starting in APA 7 and slipping into the older APA sixth-edition habits, such as listing all authors the first time then using et al. afterwards. The second most common is mixing the ampersand "&" (correct in APA parenthetical citations) with the word "and" (correct in MLA and in APA running prose) within the same paper.

Pick the style and write it across every reference. If you have copied citations from older sources, check each one against the current edition of the manual. A find-and-replace on "&" in a Word document will surface inconsistent ampersand use in seconds.

4. Italicising the wrong element

The general rule across styles: italicise the title of the larger work, and put the title of the smaller work in quotation marks. A journal article title goes in quotation marks; the journal name is italic. A chapter title is in quotation marks; the book title is italic. A song title is in quotation marks; the album title is italic.

APA 7 deviates slightly by italicising the book title and using neither italics nor quotation marks for the chapter title within the reference list. But the principle holds: the container (the larger work) is italicised. If you italicise both or neither, the marker will flag it.

5. Wrong capitalisation in titles

Capitalisation rules differ by style and by element. APA 7 uses sentence case for book titles, chapter titles, and article titles in the reference list: only the first word, the first word after a colon, and proper nouns take capital letters. APA 7 uses title case for journal titles. MLA 9 uses title case for almost everything in Works Cited. Chicago uses title case for both book and article titles.

The mistake is applying one style's rule to another style's element. The fix is to consult the manual for each part of the entry, or to use a citation tool that handles the capitalisation automatically. Both the current APA Publication Manual and the MLA Handbook give worked examples for every common element.

6. Forgetting the issue number for paginated journals

For journals that paginate by issue (each issue restarts at page 1), the issue number is essential, because volume and page alone do not uniquely identify the article. Continuous-pagination journals (where page numbers run through the entire volume) technically allow omitting the issue, but every current style guide now wants it included for consistency.

APA 7 format: Volume(Issue), pages, with no space between volume and the parenthesis. MLA 9 format: vol. X, no. Y, year, pp. xx-yy. Always include both volume and issue.

7. Incomplete or wrong publication dates

Books take a single year. Journal articles take a single year. Newspaper and magazine articles, blog posts, and webpages take a full date. Mixing this up is common: writers leave a journal article as "(2021, March 14)" instead of "(2021)", or shorten a news article to a bare year. The marker can usually find the full date in seconds and will flag the inconsistency.

APA 7 uses the format (2024, March 12). MLA 9 uses 12 Mar. 2024. Harvard uses (2024) in-text but 12 March in the reference list. Chicago uses March 12, 2024 (American format) or 12 March 2024 (British format). Match the convention to the style guide.

8. Treating a database as a publisher

JSTOR, ProQuest, EBSCO, and similar are databases, not publishers. The publisher of an article in Modern Fiction Studies is Johns Hopkins University Press. JSTOR is the platform through which you accessed it. APA 7 dropped database information for journal articles with DOIs; MLA 9 keeps the database name as a secondary container, italicised, after the journal volume and issue. Harvard varies by institution.

For a book accessed through a database such as ProQuest Ebook Central, the publisher is the original publisher of the book, and you note the database after. Never list the database as the publisher.

9. Skipping page numbers on direct quotations

Every direct quotation needs a page number, in every major style. A quotation without a page number is harder for the marker to verify and often leads to a query. The format is p. 47 or pp. 47-48 in APA and Harvard, a bare number after the surname (Smith 47) in MLA, and a page after a comma in Chicago.

Paraphrasing is more flexible. APA 7 now encourages page numbers for paraphrases drawn from a specific part of a long work, though it does not strictly require them. Including a page reference where you can is a sign of careful work.

10. Hanging indent done with the Tab key

The hanging indent on reference list entries should come from the paragraph indentation setting, not from manually pressed Tab keys. If you change the font, add a new entry, or copy and paste the list elsewhere, manual tabs fall out of alignment immediately and require re-formatting.

In Microsoft Word, highlight all entries and press Ctrl+T (Cmd+T on macOS) to apply a half-inch hanging indent in one step. In Google Docs, select the entries, open Format, Align & indent, Indentation options, and choose "Hanging" from the Special indent dropdown. In LibreOffice Writer, use Format, Paragraph, Indents & Spacing.

11. Citing sources you have not actually read

If you found a reference cited in another paper and have not read the original, you cannot cite the original directly. The proper move is to cite the secondary source using the "as cited in" convention. In APA: (Smith, 1995, as cited in Patel, 2021). The reference list contains the Patel entry, not the Smith one, because you read Patel.

The temptation is to cite the original because it sounds more authoritative, but markers can usually tell, especially if the secondary source has misrepresented the original. The honest approach is also the safer one.

12. Inconsistent formatting of online news and blog citations

Online sources cause more last-minute reformatting than any other type. The same New York Times article cited four times in one paper might appear with slightly different URLs, sometimes with the "https://", sometimes without, sometimes with a tracking parameter at the end. All four entries should match the same canonical version.

Strip tracking parameters from URLs before pasting them. The text after a "?" in a URL (such as ?utm_source=...) is almost always tracking metadata that the publisher does not need to identify the article. Use the cleanest possible URL, ideally the one that appears in the article's "permalink" or "share" button. Check that the URL still resolves to the article when you click it.

A quick pre-submission checklist

Five minutes of checking saves marks. Read through the reference list once, looking only for these things: do all journal articles have DOIs where DOIs exist? Are author orders correct? Is the style consistent across the entire list? Are titles italicised at the right level? Are dates in the format the style guide requires? If those five questions are clean, the list is probably fine.

Then read the in-text citations alongside the reference list, checking that every in-text citation has a corresponding reference entry and that every reference entry is actually cited somewhere in the body. An "uncited reference" in the list (one that does not appear in the body) is grounds for removal in most styles. An "unreferenced citation" (one in the body with no entry in the list) is a serious error that markers will always flag.

What to do next

Build consistent references with the Phrasit citation generator, review the rules for APA 7 or MLA 9, and compare consecutive drafts with the text comparator to see exactly which references changed between revisions.