How to Reference, Number Sources, and Format a Reference List
How numbered citations work, how to order your reference list, how to cite journal articles, books, and websites, what ICMJE actually says, and where students go wrong in health science papers.
Vancouver style looks straightforward on the surface. You number your sources as you go. Then you list them at the end. But the moment you hit a source with eight authors, a government report without a named author, or a journal article accessed through a database, the rules get specific fast. This guide covers how the system actually works — the logic behind it, the format for every common source type, and the places where students consistently drop marks.
What This Guide Covers
What Vancouver Style Is and Where It Comes From
Vancouver style is a numbered referencing system. Every source gets a number when it first appears in your text. That number stays with that source for the entire paper. Your reference list at the end is ordered by those numbers — not by author name, not alphabetically.
The system came out of a 1978 meeting of medical journal editors in Vancouver, Canada. Those editors needed a consistent way for researchers around the world to submit manuscripts to different journals without reformatting references each time. The result was a standard that eventually became the basis for the ICMJE Recommendations — the International Committee of Medical Journal Editors’ guidelines, which are the actual authority behind what most people call “Vancouver style.”
Numbered, Not Alphabetical
Sources are numbered in the order they first appear in the text. Reference 1 is the first source cited, reference 2 is the next new source, and so on. The list at the end follows that same numerical order.
Reuse the Same Number
If you cite a source again later in the paper, you do not give it a new number. You reuse the original one. This is one of the things that makes Vancouver different from author-date systems like APA or Harvard.
Reference List at the End
The reference list is headed “References” and lists sources in numerical order. It is not sorted by author. Entry 1 is the first source you cited, wherever that appears in the paper.
Vancouver style has a core set of rules from ICMJE, but universities and departments often apply their own preferences on top — whether to use superscript or square brackets, whether to include DOIs, whether “et al.” kicks in at three authors or seven. This guide covers ICMJE-standard Vancouver. Check your module handbook or assignment brief for institution-specific variations before you start referencing.
How the Numbering System Works
The logic is simple. The application takes a bit of practice. Here is exactly how the numbering system should work from sentence one of your paper.
The First Source You Cite Gets Number 1
Wherever in the paper you first reference a source — introduction, methods, wherever — that source becomes reference 1. You add the number at that point in the text. The source gets entry number 1 in your reference list. Simple so far.
Each New Source Gets the Next Available Number
The next source you cite that has not appeared before gets number 2. Then 3, then 4. The number follows the order of first appearance in the text, reading from top to bottom. Not in order of importance. Not alphabetically. First appearance only.
If You Cite a Source Again — Reuse Its Number
This is where Vancouver differs from most other systems. If you cited Smith et al. as reference 4, and you cite them again in your discussion section, you use (4) again — not a new number. The reference list still only has one entry for that source. The same number can appear in the text as many times as needed.
Citing Multiple Sources at One Point
You can cite more than one source at the same point in the text. List the numbers separated by commas with no spaces: (1,3,5). For a consecutive range, use a hyphen: (1-3) instead of (1,2,3). Put them in numerical order, lowest to highest. Do not rearrange them by importance or relevance.
The Reference List Follows the Same Order
When you have finished writing, your reference list starts at 1 and goes up to however many sources you have used. Entry 1 matches the first in-text citation, entry 2 matches the second new source cited, and so on. Check it: every number in your text should have a corresponding entry in the list, and every entry in the list should be cited somewhere in the text.
This is where Vancouver causes the most pain in practice. If you add a new source in the introduction after you have already written your results section, every number that follows shifts. That reference 4 becomes reference 5, reference 5 becomes reference 6, and so on — and every in-text citation in the affected part of the paper needs updating too. Use reference management software (Zotero, Mendeley, EndNote) to handle this automatically. Doing it by hand on a long paper is a reliable route to numbering errors.
In-Text Citations: Superscript, Brackets, and Parentheses
Vancouver allows three formats for the in-text citation number. Which one you use depends on your institution, your department, or the journal you are submitting to. All three mean the same thing — they just look different on the page.
Superscript Number
The most common format in published journals. The number appears raised above the text line, directly after the relevant word or sentence, before any punctuation — or after a comma or full stop depending on the context. No brackets. Example: Studies have shown a significant correlation between sleep deprivation and immune function.3
Square Brackets
Common in many university and health science settings. The number appears in square brackets, inline with the text. Example: Studies have shown a significant correlation between sleep deprivation and immune function [3]. Some departments prefer this format because it is clearer in typed work and does not require superscript formatting.
Parentheses
Less common but used by some institutions. The number appears in round brackets, inline. Example: Studies have shown a significant correlation between sleep deprivation and immune function (3). Parentheses are also used in APA and Harvard, so check that your reader will not confuse this for an author-date citation — the context usually makes it clear.
Multiple Sources at One Point
List numbers in order, separated by commas: [1,3,5] or ¹·³·⁵ in superscript. For a consecutive range: [1-3] instead of [1,2,3]. If using superscript for multiple sources, separate with a hyphen for ranges or a comma for non-consecutive: ¹⁻³ or ¹,³,⁵. Always put numbers in ascending numerical order.
How to Format the Reference List
The reference list is headed “References” — not “Bibliography,” not “Works Cited.” It goes at the end of the paper on a new page. Numbered, in the order sources first appeared in the text. Each entry gets one line per source (or runs on to subsequent lines if it is long — but no blank lines between entries of the same source).
The reference list runs 1, 2, 3… in the order sources were first cited. If you cited a textbook first and a journal article second, the textbook is reference 1, the journal article is reference 2 — regardless of author name or publication date. Do not alphabetise. Do not reorder by source type.
If you cited reference 5 twelve times across your paper, it still only appears once in the reference list — as entry number 5. The reference list entry does not change or get extended because the source was cited multiple times. It is a single record of the source, not a record of every citation.
In Vancouver style, author names are written as: Last name, then initials of first and middle names — no periods after each initial, no space between initials. Example: Smith AB, not Smith, A.B. or Smith, Andrew B. This is different from APA (which uses periods and a comma after the last name) and from Chicago (which spells out first names). Get the format right before anything else.
ICMJE standard: list all authors up to six. If a source has seven or more authors, list the first six and add “et al.” after the sixth. Some institutions use three as the cut-off — check your brief. “et al.” is not italicised in Vancouver style. It is followed by a full stop.
This is one of Vancouver’s distinctive features. Journal names in the reference list are abbreviated using the standard abbreviations from the National Library of Medicine (NLM) catalogue — for example, The Lancet becomes Lancet, The New England Journal of Medicine becomes N Engl J Med. The full title is never used in Vancouver reference list entries. NLM journal abbreviations are searchable at ncbi.nlm.nih.gov/nlmcatalog/journals.
In Vancouver, article titles use sentence case — only the first word and proper nouns are capitalised. “Mental health problems and social media exposure during COVID-19 outbreak” — not “Mental Health Problems and Social Media Exposure During COVID-19 Outbreak.” Book titles follow the same rule in Vancouver, unlike APA which uses title case for books.
Citing Journal Articles
Journal articles are the most common source type in health science papers. Get this format right and the logic extends to almost everything else.
Standard Format
Notes: No space between year, semicolon, volume, and issue. Issue number in parentheses immediately after volume number, no space. Colon then page range with no space. If the article has a DOI, add it at the end: doi:10.XXXX/XXXXX or as a URL.
Using “The New England Journal of Medicine” instead of “N Engl J Med” is a Vancouver formatting error. Always look up the NLM-approved abbreviation for any journal you cite. For journals without an official NLM abbreviation — newer journals, regional journals — use the journal’s own stated abbreviation, or abbreviate using the standard rules (omit prepositions, abbreviate common words like Journal to J, Medicine to Med).
Citing Books and Book Chapters
Standard Format
Edition: write as “2nd ed.”, “3rd ed.”, etc. — not “Second Edition.” Place of publication: city name only (not country unless ambiguous). Publisher and year separated by a semicolon. If citing specific pages: add p. X or p. X-Y at the end.
Standard Format
“editor” or “editors” is abbreviated as “editor” or “editors” — not “ed.” in Vancouver when it refers to the person (unlike some other styles). The chapter page range goes at the end with “p.” before it.
Citing Websites and Online Sources
Web sources in Vancouver need an access date. Web content changes and disappears. Without it, there is no way to verify what you read at the time you read it. This is not optional.
Standard Format
If no author: start with the organisation or body responsible for the content. “[Internet]” follows the title — this signals the source type. Update date and cited (access) date in square brackets. End with the full URL on the same line — no full stop after the URL.
If you accessed a journal article through PubMed, Google Scholar, or a university database, you still cite it as a journal article — not as a website. The format follows the standard journal article structure. Add the DOI if one is available. You do not add an access date for journal articles, even if you read them online — journal articles have stable content and a fixed DOI. Access dates are only for webpages and other online content that may change.
Other Source Types: Reports, Theses, Conference Papers
Standard Format
If accessed online, add [Internet] after the title, and the access date and URL as for a website.
Standard Format
Use “dissertation” for a PhD-level work, “thesis” for a master’s-level work — or follow the terminology used by the institution that awarded it. If accessed online, add [Internet], update/cite dates, and URL.
Standard Format
Vancouver vs APA vs Harvard
Students who have used APA or Harvard before sometimes try to apply the same logic to Vancouver. The systems are different in ways that matter. Here is where they diverge.
| Feature | Vancouver | APA 7th | Harvard |
|---|---|---|---|
| In-text citation format | Number: ¹ or [1] or (1) | Author-date: (Smith, 2021) | Author-date: (Smith 2021) |
| Reference list order | Numerical — order of first appearance in text | Alphabetical by author’s last name | Alphabetical by author’s last name |
| Author name format | Last name then initials: Smith AB | Last name, then initials: Smith, A. B. | Last name, then initials: Smith, A.B. |
| Journal names | Abbreviated: N Engl J Med | Full name, italicised: New England Journal of Medicine | Full name, italicised: New England Journal of Medicine |
| Article title case | Sentence case: only first word capitalised | Sentence case | Sentence case |
| Book title case | Sentence case | Sentence case | Sentence case |
| et al. threshold | After 6 authors (ICMJE); some depts use 3 | After 20 authors (list first 19) | After 3 authors (varies by institution) |
| Primary use field | Medicine, nursing, health sciences | Psychology, education, social sciences | Varies — many UK disciplines |
What Vancouver Does That Others Don’t
- Assigns a permanent number to each source — no author name in text at all
- Reference list ordered by citation order, not alphabetically
- Journal names abbreviated using NLM standard
- Author initials with no periods and no spaces between them
- Multiple consecutive sources shown as a range: [1-4]
- Access date required for all webpages
- Clean, number-only text — no author names interrupting sentences
When Vancouver Is a Better Fit Than APA
- You are citing many sources at a single point — a list of numbers is less disruptive than multiple author-date pairs
- Recency of publication is less critical than in social sciences — medical knowledge is cumulative, not always superseded
- The paper will be read by clinicians who expect numbered references
- Your department, module, or target journal specifies it
- The paper covers a clinical topic where ICMJE guidelines apply
Common Errors That Cost Marks
Alphabetising the Reference List
The most common Vancouver mistake. Students used to APA or Harvard instinctively sort references alphabetically. In Vancouver, the list follows the order of first citation in the text. Reference 1 is the first source you cited, full stop. Alphabetising produces the wrong list order and mismatches with in-text numbers.
Build the List as You Write
Add each source to the reference list the moment you first cite it in the text, numbered in the order it appears. If you wait until the end to compile the list, you will have to reconstruct the citation order from the paper — which is slower and more error-prone. Reference management software like Zotero or Mendeley can maintain the list automatically as you insert citations.
Giving the Same Source Two Different Numbers
If you cited a source as reference 4 in your introduction, and then forgot that when writing your discussion — assigning it a new number like 11 — you now have two entries for the same source. The reference list has a duplicate. The in-text numbers are inconsistent. This is caught by markers and deducted accordingly.
Check Every Number Before Submitting
Before you submit, go through every in-text citation and check it against the reference list. Every number in the text should have exactly one matching entry. Every entry in the list should appear at least once in the text. No gaps, no duplicates. If you have used reference software, run its error-check function. If you have done it manually, do this check twice.
Spelling Out Journal Names in Full
“The New England Journal of Medicine” in a Vancouver reference list is wrong. Journal names must be abbreviated using NLM standard abbreviations. Writing the full name suggests either unfamiliarity with Vancouver style or reliance on a citation tool that did not apply the abbreviation correctly. Both produce the same formatting error.
Look Up Every Journal Abbreviation
Do not guess abbreviations. Look them up at the NLM journal catalogue (ncbi.nlm.nih.gov/nlmcatalog/journals) or through PubMed — search for the journal and the abbreviation appears in the catalogue record. This takes 30 seconds per journal and prevents a formatting error that appears on every single article entry.
Wrong Author Name Format
Periods after initials (Smith A.B.), commas after the last name without periods (Smith, AB), or spelling out first names (Smith Andrew B.) — all wrong for Vancouver. The correct format is: Last name then initials, no periods, no comma after the last name, no spaces between initials. Smith AB. Jones CD. That’s it.
Last Name + Initials, No Punctuation Between Initials
Smith AB, not Smith, A.B. For two authors: Smith AB, Jones CD. The comma separates authors from each other, not the last name from the initials. Apply this format consistently across every entry in the reference list. Inconsistency — some entries with periods, some without — is just as penalised as using the wrong format throughout.
Missing the Access Date for Websites
Web content changes. A WHO fact sheet updated between when you cited it and when your marker reads the paper looks different — or no longer exists. Vancouver requires the date you accessed the page, in the format [cited Year Mon Day]. Leaving it out is a formatting error. “I accessed it in March” is not sufficient — it needs the specific date.
Record Access Dates When You Read Each Source
Note the access date for every website source at the time you read it — not when you format the reference list weeks later. It takes five seconds. Reconstructing it afterward requires you to hope the page still exists, check browser history, or make something up — none of which is reliable. If you use a reference manager, set it to automatically record access dates for web sources.
Forgetting That Numbers Shift When You Edit
You insert a new paragraph in the methods section that cites a new source. That source becomes reference 3. Everything that was 3 is now 4, everything that was 4 is now 5, and so on — and every in-text citation from that point onward needs updating. If you do not catch this, your reference list and your in-text numbers are misaligned throughout.
Use Reference Management Software for Anything Longer Than a Short Essay
Zotero, Mendeley, and EndNote all have Vancouver output styles and Word/Google Docs plugins that update citation numbers automatically when you insert or remove sources. For a dissertation, literature review, or any paper with more than ten sources, managing Vancouver references manually is a significant risk. The software is free. The time it saves — and the errors it prevents — is considerable.
Frequently Asked Questions About Vancouver Style
Vancouver Referencing Taking More Time Than the Paper Itself?
Our specialist team handles Vancouver referencing and full academic writing support — essays, reports, literature reviews, and dissertations for health science students at every level of study.
Academic Writing Services Get StartedThe Part of Vancouver That Actually Matters
The rules here are specific but not complicated. Number your sources in the order they first appear. Reuse those numbers. Abbreviate journal names. Keep your author format consistent. Build the reference list as you write, not after.
What trips most students up is not ignorance of the rules — it is the cascade effect when sources are added or removed during drafting. That is the argument for using reference management software from the start. Zotero is free. It handles Vancouver numbering automatically. It updates every in-text citation when the list changes. For a short essay with six sources, you can manage it manually. For a literature review or a dissertation with 40 or 50 references, manual management is an unnecessary risk.
One last thing worth saying clearly: Vancouver style varies slightly between institutions. The ICMJE guidelines set the standard, but your university’s health faculty handbook may specify superscript over square brackets, or three authors before “et al.” rather than six. Read your brief. When your brief and this guide disagree, follow the brief.
For support with Vancouver referencing, citation formatting across other styles, and broader health science academic writing — our citation and referencing resources, annotated bibliography guide, and academic writing services cover every level of study.
Continue building your referencing skills: citation and referencing guide · annotated bibliography · Chicago format guide · Turabian citation guide · Harvard citation guide · essay writing · research paper writing · dissertation and thesis writing · proofreading and editing