The most common in-text citation errors are mismatches with the reference list, missing page numbers for quotations, wrong punctuation (especially commas in MLA), and incorrect handling of multiple authors. Each one is easy to fix once you know the pattern your style guide expects. Below are twelve mistakes we see constantly in student papers, with a corrected version of each.
All examples use fictional sources, so you can focus on the format rather than the content.
Why small citation errors matter
An in-text citation does one job: it points the reader to an exact entry in your reference list or works-cited page. When the pointer is broken, the reader can't verify your claim, and an instructor may wonder whether you understood where the idea came from.
Most errors are not dishonest. They come from mixing APA and MLA habits, copying a format from an old paper, or fixing the reference list at the last minute without updating the text. Still, they cost marks, and a pattern of missing citations can look like plagiarism even when it isn't.
The quick reference: APA vs. MLA basics
| Element | APA 7th edition | MLA 9th edition |
|---|---|---|
| Basic parenthetical | (Hollis, 2021) | (Hollis) |
| With a page | (Hollis, 2021, p. 42) | (Hollis 42) |
| Two authors | (Hollis & Varga, 2021) | (Hollis and Varga 42) |
| Three or more authors | (Hollis et al., 2021) | (Hollis et al. 42) |
| Narrative form | Hollis (2021) argued... | Hollis argues... (42). |
Keep this table nearby while you edit. Most of the errors below are a cell from one column used in the other.
1. The citation doesn't match the reference list
You cite (Tamberlane, 2020) in the text, but the reference list has "Tamberlain, R. (2019)." Or the source is missing from the list entirely.
Fix: The name in your in-text citation should match the first word of the corresponding reference entry, and in APA the year should match too. Do a final pass where you check every citation against the list, and the list against the text, since entries for sources you dropped should be deleted.
2. Missing page number on a direct quotation
"Most urban gardens fail in their second year, not their first" (Okafor, 2022).
Fix: Quotations need a locator.
- APA: (Okafor, 2022, p. 118)
- MLA: (Okafor 118)
If the source has no page numbers, use what it does have: a paragraph number (para. 6 in APA, par. 6 in MLA), a section heading, or a timestamp for audio and video.
3. Commas in MLA citations
Writers who learned APA first often write (Okafor, 118) in MLA.
Fix: MLA uses no comma between the author and the page: (Okafor 118). A comma appears only between two different elements, such as an author and a shortened title when you cite two works by the same person: (Okafor, Second Seasons 118).
4. Using "p." in MLA or leaving it out in APA
Fix: APA uses "p." for one page and "pp." for a range: (Okafor, 2022, pp. 118–119). MLA uses the number alone: (Okafor 118–19). Note that MLA allows the shortened second number in a range, while APA writes both in full.
5. Ampersand vs. "and"
In APA, two authors are joined with "&" inside parentheses but with "and" in running text.
- Correct: (Lindqvist & Moreau, 2023)
- Correct: Lindqvist and Moreau (2023) found...
- Incorrect: Lindqvist & Moreau (2023) found...
MLA uses "and" in both places.
6. Listing every author when you should use et al.
APA 7th edition simplified this: for three or more authors, cite the first author plus "et al." from the first citation onward. MLA does the same for three or more authors.
Fix: (Ferreira et al., 2020) in APA, (Ferreira et al. 77) in MLA. Remember that "et al." has a period after "al" only, and no period after "et."
7. Including first names or initials
(Daniel Ferreira, 2020)
Fix: Use surnames only. The one exception, in both APA and MLA, is when two different first authors share a surname; then you add initials to tell them apart: (A. Ferreira, 2020) and (L. Ferreira, 2018) in APA, (A. Ferreira 77) in MLA.
8. Putting the period in the wrong place
For a quotation that sits inside your sentence, the citation comes before the final period:
"Second seasons decide everything" (Okafor, 2022, p. 120).
For a block quotation (40 or more words in APA, more than four lines of prose in MLA), the order flips: the quotation ends with its period, and the citation follows with no period after it.
9. Citing the year in MLA or skipping it in APA
APA is an author-date system, so the year is required every time, including narrative citations: Okafor (2022) noted... MLA is author-page, so the year normally does not appear in the citation at all.
Fix: Pick the right system for the paper and stay in it. Mixed citations are the most visible sign of a paper assembled from different drafts.
10. Handling sources with no author or no date badly
Writing "(Anonymous)" or "(n.a.)" is a frequent mistake. (Use "Anonymous" only when the work is actually signed that way.)
Fix: If there is no author, move the title into the author position. In APA, use a shortened title and the year: ("Rising Rents," 2024). In MLA, use a shortened title: ("Rising Rents"). If there is no date in APA, write n.d.: (Harbor Data Lab, n.d.). For a full walkthrough, see our guide on citing sources with no author.
Citation GeneratorAPA, MLA, Chicago and more11. Citing the original when you only read the secondary source
Say you read a book by Varga that quotes an interview with Delacroix, but you never saw the interview yourself. Citing Delacroix directly implies you did.
Fix:
- APA: (Delacroix, as cited in Varga, 2019). Only Varga goes in the reference list.
- MLA: (qtd. in Varga 64). Only Varga goes in the works-cited list.
Use this sparingly. If the original is available, find it and cite it directly. Our guide on how to quote a quote covers the details.
12. Over-citing the same source in one paragraph
Repeating (Okafor, 2022) after every sentence makes a paragraph hard to read.
Fix: In APA, once you have cited a source narratively in a paragraph, you can omit the year in later narrative mentions in the same paragraph, as long as it stays clear which source you mean (parenthetical citations keep the year). In MLA, cite again when you add new page references or when another source has come in between. If one paragraph leans heavily on one source, consider whether you're summarizing too much and analyzing too little.
A five-minute checklist before you submit
Run through this list with your reference page open next to your draft:
- Every in-text citation has a matching reference entry, spelled the same way.
- Every reference entry is cited at least once in the text.
- Every direct quotation has a page number or other locator.
- APA citations include the year; MLA citations don't.
- No commas between author and page in MLA.
- "&" only inside APA parentheses; "and" everywhere else.
- Three or more authors use "et al."
- Periods sit after the parenthesis (except for block quotes).
A citation generator can format the reference entries, but it can't check that your text matches them. That last step is on you, and it's the one that catches the most problems.
Key takeaways
- Most citation errors come from mixing APA and MLA conventions. Decide which style you're using and check each citation against it.
- Quotations always need a locator: page, paragraph, section or timestamp.
- The name you cite in the text should be the first word of a reference-list entry.
- When a rule seems unclear for an unusual source, check your instructor's preferences or the current edition of the style guide rather than guessing.