Harvard referencing follows the author-date convention — every in-text citation pairs with a full entry in your reference list. Most mistakes fall into three categories: formatting errors (capitalisation, italics, punctuation), in-text citation errors (missing page numbers, wrong use of et al.), and reference list errors (wrong element order, inconsistent styling). Because Harvard has no single governing manual, institutional guides can differ on fine details — but the mistakes below are wrong in virtually every Harvard guide.
Mistake 1 — Confusing Harvard With APA
This is the most common misconception. Both Harvard and APA use the author-date system, so students assume they're the same thing. They are not. APA is a standardised style governed by the Publication Manual of the American Psychological Association. Harvard is a broad convention that varies between institutions.
| Feature | Harvard (Common UK Convention) | APA (7th Edition) |
|---|---|---|
| Governing body | None — institutional guides | American Psychological Association |
| Title capitalisation | Sentence case | Title case (in headings), sentence case (in references) |
| Ampersand | "and" or "&" (varies) | "&" in parentheses, "and" in narrative |
| Et al. threshold | 3 or 4 authors (varies) | 3+ authors |
| "Available at:" for URLs | Common in UK guides | Not used — DOIs and URLs appear directly |
| Access dates | Often required | Only for sources without a fixed publication date |
The fix: Identify which style your module requires. If it says "Harvard," follow your institution's Harvard guide — not the APA manual.
For a detailed comparison, see Harvard vs. APA — What's the Difference?.
Mistake 2 — Wrong Capitalisation in Titles
Many students title-case everything in their reference list — capitalising every major word. Most Harvard guides require sentence case: capitalise only the first word of the title and subtitle, plus any proper nouns.
✗ Walker, M. (2017) Why We Sleep: The New Science of Sleep and Dreams. London: Penguin Books.
✓ Walker, M. (2017) Why we sleep: the new science of sleep and dreams. London: Penguin Books.
Journal names are the exception — they keep their published capitalisation:
✓ Diekelmann, S. and Born, J. (2010) 'The memory function of sleep', Nature Reviews Neuroscience, 11(2), pp. 114–126.
The fix: Capitalise only the first word, the first word after a colon or dash, and proper nouns. Leave everything else in lower case.
Mistake 3 — Italics and Quotation Marks on the Wrong Elements
Harvard uses formatting to distinguish between standalone works and parts of larger works:
| Source Type | Formatting | Example |
|---|---|---|
| Book | Italics | Why we sleep |
| Journal name | Italics | Nature Reviews Neuroscience |
| Website name | Italics | BBC News |
| Journal article | Single quotation marks | 'The memory function of sleep' |
| Book chapter | Single quotation marks | 'Sleep and adolescence' |
| Web page title | Single quotation marks | 'About us' |
A common error is italicising article titles or putting book titles in quotation marks:
✗ Diekelmann, S. (2010) The memory function of sleep, 'Nature Reviews Neuroscience'…
✓ Diekelmann, S. (2010) 'The memory function of sleep', Nature Reviews Neuroscience…
The fix: Ask yourself — is this a whole work (book, journal, website) or a part of a work (article, chapter, page)? Whole works get italics; parts get single quotation marks.
Mistake 4 — Missing Page Numbers on Direct Quotes
Every direct quote must include a locator — a page number, paragraph number, or other indicator that tells the reader exactly where the quoted words appear. Omitting it is one of the most common citation errors.
✗ Walker describes sleep as 'the single most effective thing we can do to reset our brain and body health each day' (Walker, 2017).
✓ Walker describes sleep as 'the single most effective thing we can do to reset our brain and body health each day' (Walker, 2017, p. 7).
For sources without page numbers, use whichever locator is available:
| Locator Type | Format |
|---|---|
| Paragraph number | para. 4 |
| Section heading | 'Symptoms' section |
| Chapter | ch. 3 |
| Timestamp | 14:32 |
The fix: Every time you use quotation marks, include a locator. No exceptions.
For full quoting guidelines, see How to Use Direct Quotes in Harvard Referencing.
Mistake 5 — Punctuation in the Wrong Place
The full stop goes after the parenthetical citation, not inside the quotation marks or before the parentheses. This is a punctuation error that appears in almost every first draft.
✗ '…brain and body health each day.' (Walker, 2017, p. 7)
✓ '…brain and body health each day' (Walker, 2017, p. 7).
For block quotes, the citation goes at the end of the block — some guides place it after the final full stop, others before. Be consistent.
The fix: Full stop after the closing parenthesis. Always.
Mistake 6 — Using Et Al. in the Reference List
Et al. is a shorthand used only in in-text citations — it tells the reader "and others" without listing every name. In the reference list, you must list all authors, no matter how many there are.
✗ Nguyen, T. et al. (2022) Urban sustainability: a global perspective. Oxford: Oxford University Press.
✓ Nguyen, T., Patel, R., Okamoto, Y. and Fischer, L. (2022) Urban sustainability: a global perspective. Oxford: Oxford University Press.
Some Harvard guides set a maximum — for example, listing up to six authors and then using et al. for the seventh onward. But the default rule is: spell them all out.
The fix: In-text citations can use et al. The reference list cannot (unless your guide explicitly sets an upper limit).
For detailed rules on multi-author citations, see Harvard Citation With Multiple Authors.
Mistake 7 — Inconsistent Formatting Across Entries
Inconsistency is harder to spot than a single error — but it's just as damaging to your marks. Common inconsistencies include:
- Mixing "and" and "&" between authors
- Using access dates on some web sources but not others
- Capitalising titles differently across entries (sentence case in one, title case in another)
- Including "Available at:" for some URLs but not others
- Single quotation marks on some article titles, double on others
The fix: After writing your reference list, read through it entry by entry and check that every element follows the same convention. Better yet, create a template entry and model every new reference on it.
Mistake 8 — Missing or Incorrect Access Dates
For online sources, most Harvard guides require an access date — the date you viewed the page. Students frequently forget this, format it inconsistently, or confuse the access date with the publication date.
✗ NHS (2024) Mental health support. Available at: https://www.nhs.uk/mental-health.
✓ NHS (2024) Mental health support. Available at: https://www.nhs.uk/mental-health (Accessed: 12 January 2025).
The fix: Add "(Accessed: Day Month Year)" at the end of every online reference. Use the format your institution specifies — most UK Harvard guides use "Accessed: 12 January 2025."
Mistake 9 — Citing Sources Not in the Reference List (and Vice Versa)
Every in-text citation must have a matching entry in the reference list. Every entry in the reference list must be cited at least once in your text. These two lists must mirror each other perfectly.
Common causes:
- Deleting a citation during editing but forgetting to remove the reference list entry
- Adding a reference list entry "just in case" without actually citing it
- Citing a source as (Smith, 2020) but listing it under a different year in the reference list
The fix: Before submitting, cross-check both lists. Search your document for each author surname in the reference list and confirm it appears as an in-text citation — and vice versa.
Spot the Errors
Test yourself with this paragraph. There are five Harvard referencing errors — see if you can identify them all before reading the answers below.
Recent research suggests that sleep deprivation "negatively impacts cognitive function." (Walker, 2017). Multiple studies have confirmed this finding (Nguyen et al, 2022), with Diekelmann and Born (2010) describing sleep as a state that optimises The Memory Function of Sleep. The World Health Organisation (2024) recommends at least seven hours of sleep per night. The NHS (2024) provides guidance on Mental Health Support, available at https://www.nhs.uk/mental-health.
Answers:
- Double quotation marks — most UK Harvard guides use single: 'negatively impacts cognitive function'
- Full stop before the citation — should be: …function' (Walker, 2017, p. X). (Also missing a page number — it's a direct quote)
- Missing full stop after "et al" — should be: (Nguyen et al., 2022) — et al. always has a full stop because it's an abbreviation
- Title capitalisation and formatting error — 'The memory function of sleep' should be in single quotes with sentence case, not italicised with title case (it's a journal article, not a book)
- Missing access date — the NHS reference needs (Accessed: Day Month Year)
Pre-Submission Checklist
Use this checklist before submitting any paper with Harvard references:
- Every in-text citation has a matching entry in the reference list
- Every reference list entry is cited at least once in the text
- Titles in the reference list use sentence case
- Standalone works are italicised; parts of works are in single quotation marks
- Direct quotes include a page number or equivalent locator
- Full stops go after the parenthetical citation, not before
- Et al. is used only in in-text citations, not in the reference list
- "and" / "&" usage is consistent throughout
- Online sources include an access date
- The reference list is in alphabetical order by author surname
- All URLs are present, unshortened, and not followed by a full stop
What's Next?
Now that you know what to watch out for, explore these related guides:
- Harvard Referencing Style — the complete overview of how Harvard referencing works
- Harvard In-Text Citations — detailed rules for parenthetical and narrative citations
- Harvard Reference List — formatting rules for every element of a reference list entry
- Harvard General Format — page layout, margins, spacing, and title page conventions
