How do I cite a Cochrane review, or the Cochrane Handbook?

A Cochrane review is a journal article in Cochrane Database of Systematic Reviews, so use the journal-article pattern (NLM sample #1) and put the review's article number where the page range would go, as NLM sample #36 does for an "article with document number in place of traditional pagination" (Williams JS, Brown SM, Conlin PR. Videos in clinical medicine. Blood-pressure measurement. N Engl J Med. 2009 Jan 29;360(5):e6). The Cochrane Handbook is a book, not an article in that journal, so cite it as a monograph on the internet following NLM sample #37 — editors, title, [Internet], place, publisher, year, [cited date], Available from: URL. Take every element from the version you actually read, since the Handbook is revised.

How do I handle articles in press?

NLM's samples page (item #34) notes: “NLM prefers ‘Forthcoming’ rather than ‘In press’ because not all items will be printed.” Its own sample is: “Tian D, Araki H, Stahl E, Bergelson J, Kreitman M. Signature of balancing selection in Arabidopsis. Proc Natl Acad Sci U S A. Forthcoming 2002.” For an article published online ahead of print, add “Epub” and the date, as sample #18 does.

How do I cite a clinical trial registration?

NLM's samples show the registration number appended to the article it belongs to: “Trachtenberg F, Maserejian NN, Soncini JA, Hayes C, Tavares M. Does fluoride in compomers prevent future caries in children? J Dent Res. 2009 Mar;88(3):276-9. PubMed PMID: 19329464. ClinicalTrials.gov registration number: NCT00065988.” To cite a registry record itself, follow the database-part pattern: [Registry name] [Internet]. [Place]: [Publisher]. [Years] - . Identifier [NCT number], [Record title]; [date] [cited date]. Available from: [URL].

Should I include PubMed IDs (PMIDs)?

It is optional. Under sample #1, NLM lists it as “Optional: Addition of a database's unique identifiers, such as the PubMed PMID, for the citation:” and gives this sample: “Forooghian F, Yeh S, Faia LJ, Nussenblatt RB. Uveitic foveal atrophy: clinical features and associations. Arch Ophthalmol. 2009 Feb;127(2):179-86. PubMed PMID: 19204236; PubMed Central PMCID: PMC2653214.” The identifiers go at the end, after the rest of the reference.

How to Cite in NLM Style: National Library of Medicine Guide

Q: What's the difference between NLM and Vancouver style?

They are two names for closely related things. "Vancouver" refers to the reference style in the ICMJE Recommendations, which NLM's samples page notes was "formerly the Uniform Requirements for Manuscripts"; that style is, in NLM's words, "based on the National Information Standards Organization NISO Z39.29-2005 (R2010) Bibliographic References as adapted by the National Library of Medicine for its databases," with fuller detail in Citing Medicine. In practice they are interchangeable, but check your target journal's instructions.

This guide will help you cite sources in NLM format, the reference style behind PubMed, MEDLINE and most medical journals. If you're writing for biomedical publications or citing clinical research, NLM style is very likely what your journal's instructions mean.

Every reference example below is copied from a source we can point you at: either NLM's own Samples of Formatted References for Authors of Journal Articles (numbered items, referred to below as "NLM sample #n") or the relevant chapter of Citing Medicine.

Official Source

NLM style is set out in Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers, 2nd edition, a free resource maintained by the National Library of Medicine on the NCBI Bookshelf. NLM also publishes a shorter page of formatted samples for journal authors, which is the fastest way to check a format.

NLM's samples page states the relationship between the standards plainly: the International Committee of Medical Journal Editors (ICMJE) gives guidance to authors in its Recommendations, and "the recommended style for references is based on the National Information Standards Organization NISO Z39.29-2005 (R2010) Bibliographic References as adapted by the National Library of Medicine for its databases."

In-Text Citations

Citing Medicine specifies how a reference is written; it does not prescribe a system of in-text citation. That comes from your journal, and for biomedical journals it usually comes from ICMJE, whose manuscript preparation recommendations say:

"References should be numbered consecutively in the order in which they are first mentioned in the text. Identify references in text, tables, and legends by Arabic numerals in parentheses."

Chocolate has been studied for effects on mood and cognition (1), and for effects on vascular function (2).

Many journals set those numerals as superscripts instead, and some fields use author–date. Follow your journal's instructions; the reference-list format stays the same either way.

Key NLM characteristics:

Author surname followed by initials, with no comma between them, no space between initials, and no periods: Halpern SD
Abbreviated journal titles per the NLM Catalog
Access dates for online sources, written [cited 2024 Jun 15]
Available from: before a URL
Punctuation carefully specified — a semicolon before volume, a colon before pages

Reference List Format

Journal Articles

Standard journal article (NLM sample #1):

Halpern SD, Ubel PA, Caplan AL. Solid-organ transplantation in HIV-infected patients. N Engl J Med. 2002 Jul 25;347(4):284-7.

Article with more than six authors (NLM sample #1):

Rose ME, Huerbin MB, Melick J, Marion DW, Palmer AM, Schiding JK, et al. Regulation of interstitial excitatory amino acid concentrations after cortical contusion injury. Brain Res. 2002;935(1-2):40-6.

NLM's note on that sample reads: "List the first six authors, followed by et al. […] (Note: NLM now lists all authors.)" So listing every author is current NLM practice, and the six-plus-et al. form remains acceptable.

Continuous pagination — month and issue number may be omitted (NLM sample #1):

Halpern SD, Ubel PA, Caplan AL. Solid-organ transplantation in HIV-infected patients. N Engl J Med. 2002;347:284-7.

Article with a DOI (NLM sample #36):

Zhang M, Holman CD, Price SD, Sanfilippo FM, Preen DB, Bulsara MK. Comorbidity and repeat admission to hospital for adverse drug reactions in older adults: retrospective cohort study. BMJ. 2009 Jan 7;338:a2752. doi: 10.1136/bmj.a2752. PubMed PMID: 19129307; PubMed Central PMCID: PMC2615549.

Journal article on the internet (NLM sample #36):

Abood S. Quality improvement initiative in nursing homes: the ANA acts in an advisory role. Am J Nurs [Internet]. 2002 Jun [cited 2002 Aug 12];102(6):[about 1 p.]. Available from: https://journals.lww.com/ajnonline/Fulltext/2002/06000/Quality_Improvement_Initiative_in_Nursing_Homes.31.aspx Subscription required.

Organization as author (NLM sample #2):

Diabetes Prevention Program Research Group. Hypertension, insulin, and proinsulin in participants with impaired glucose tolerance. Hypertension. 2002;40(5):679-86.

No author given (NLM sample #4):

21st century heart solution may have a sting in the tail. BMJ. 2002;325(7357):184.

Books

Personal authors (NLM sample #19):

Murray PR, Rosenthal KS, Kobayashi GS, Pfaller MA. Medical microbiology. 4th ed. St. Louis: Mosby; 2002.

Editors as author (NLM sample #20):

Gilstrap LC 3rd, Cunningham FG, VanDorsten JP, editors. Operative obstetrics. 2nd ed. New York: McGraw-Hill; 2002.

Organization as author (NLM sample #22):

American Occupational Therapy Association, Ad Hoc Committee on Occupational Therapy Manpower. Occupational therapy manpower: a plan for progress. Rockville (MD): The Association; 1985 Apr. 84 p.

Monograph on the internet (NLM sample #37):

Foley KM, Gelband H, editors. Improving palliative care for cancer [Internet]. Washington: National Academy Press; 2001 [cited 2002 Jul 9]. Available from: https://www.nap.edu/catalog/10149/improving-palliative-care-for-cancer

Book Chapters

Chapter in a book (NLM sample #23):

Meltzer PS, Kallioniemi A, Trent JM. Chromosome alterations in human solid tumors. In: Vogelstein B, Kinzler KW, editors. The genetic basis of human cancer. New York: McGraw-Hill; 2002. p. 93-113.

Note In: before the editors, and p. before the page range of the chapter.

Websites and Homepages

Whole website (NLM sample #38):

eatright.org [Internet]. Chicago: Academy of Nutrition and Dietetics; c2016 [cited 2016 Dec 27]. Available from: https://www.eatright.org/

Part of a website (NLM sample #39):

American Medical Association [Internet]. Chicago: The Association; c1995-2016 [cited 2016 Dec 27]. Office of International Medicine; [about 2 screens]. Available from: https://www.ama-assn.org/about/office-international-medicine

A copyright date takes a lower-case c, and a date range that is still open is written with a trailing dash — 2000 - .

Databases

Whole database (from Citing Medicine, chapter 24):

MeSH Database [Internet]. Bethesda (MD): National Library of Medicine (US). 2003 Apr - [cited 2011 Jul 8]. Available from: http://www.ncbi.nlm.nih.gov/mesh

Part of a database (NLM sample #41):

MeSH Browser [Internet]. Bethesda (MD): U.S. National Library of Medicine; 2002 - . Meta-analysis; [cited 2017 Dec 1]; [about 1 p.]. Available from: https://meshb.nlm.nih.gov/record/ui?ui=D017418 MeSH Unique ID: D017418.

Dissertations

NLM sample #27:

Borkowski MM. Infant sleep and feeding: a telephone survey of Hispanic Americans [dissertation]. Mount Pleasant (MI): Central Michigan University; 2002.

Citing Medicine chapter 5 shows the same pattern with an extent, and square brackets around a place that had to be inferred:

Jones DL. The role of physical activity on the need for revision total knee arthroplasty in individuals with osteoarthritis of the knee [dissertation]. [Pittsburgh (PA)]: University of Pittsburgh; 2001. 436 p.

Use [master's thesis] for master's-level work.

Conference Papers

Conference proceedings (NLM sample #24):

Harnden P, Joffe JK, Jones WG, editors. Germ cell tumours V. Proceedings of the 5th Germ Cell Tumour Conference; 2001 Sep 13-15; Leeds, UK. New York: Springer; 2002.

A paper within proceedings (NLM sample #25):

Christensen S, Oppacher F. An analysis of Koza's computational effort statistic for genetic programming. In: Foster JA, Lutton E, Miller J, Ryan C, Tettamanzi AG, editors. Genetic programming. EuroGP 2002: Proceedings of the 5th European Conference on Genetic Programming; 2002 Apr 3-5; Kinsdale, Ireland. Berlin: Springer; 2002. p. 182-91.

Preprints

NLM sample #34:

Bar DZ, Atkatsh K, Tavarez U, Erdos MR, Gruenbaum Y, Collins FS. Biotinylation by antibody recognition- A novel method for proximity labeling. BioRxiv 069187 [Preprint]. 2016 [cited 2017 Jan 12]. Available from: https://www.biorxiv.org/content/10.1101/069187v1

Clinical Resources and Drug Labels

A drug label in DailyMed, cited as a contribution to a database (Citing Medicine, chapter 24):

Sanofi-Aventis U.S. LLC. Ambien cr (zolpidem tartrate) tablet, coated. 2007 [rev. 2007 Sep; cited 2018 May]. In: DailyMed [Internet]. [2005] - . [about 20 p.]. Bethesda (MD): National Library of Medicine (US). Available from: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=404c858c-89ac-4c9d-8a96-8702a28e6e76

The whole database (Citing Medicine, chapter 24):

DailyMed [Internet]. Bethesda (MD): U.S. National Library of Medicine. [2005] - [cited 2018 May 18]. Available from: https://dailymed.nlm.nih.gov/dailymed/

For a subscription point-of-care resource such as UpToDate, follow the same database-contribution pattern and note that a subscription is required, as NLM sample #36 does for a paywalled article.

NLM Journal Abbreviations

NLM uses standardized journal title abbreviations recorded in the NLM Catalog. A few common ones:

Full Title	NLM Abbreviation	Where we checked it
The New England Journal of Medicine	N Engl J Med	NLM sample #1
BMJ	BMJ	NLM samples #4, #36
JAMA	JAMA	NLM Catalog, NLM ID 7501160
Brain Research	Brain Res	NLM sample #1
Journal of Dental Research	J Dent Res	NLM sample #1
American Journal of Nursing	Am J Nurs	NLM sample #36
Proceedings of the National Academy of Sciences of the United States of America	Proc Natl Acad Sci U S A	NLM sample #34
Nutrition Reviews	Nutr Rev	NLM Catalog, NLM ID 376405

Look up any title you are unsure of in the NLM Catalog rather than guessing — the catalogue's "Journals" search returns the exact abbreviation NLM indexes. Some titles, such as JAMA and Neurology, are their own abbreviation.

Common NLM Mistakes to Avoid

Missing access dates. For internet sources, include [cited YYYY Mon DD].
Incorrect author formatting. Smith JK, not Smith, J.K. or Smith J. K.
Wrong journal abbreviations. Verify against the NLM Catalog; invented abbreviations are a common error.
Omitting "Available from". Internet sources need Available from: before the URL.
Forgetting revision information. For resources that change, include the edition, update or revision date — [rev. 2007 Sep; cited 2018 May].
Citing an "in press" article as published. NLM's samples page prefers Forthcoming.

NLM Citation Tools

PubMed provides formatted citations — click "Cite" on any article record.

Reference managers such as Zotero include NLM/Vancouver style templates. Because the two styles follow the same ICMJE recommendations, a Vancouver template will usually satisfy an NLM requirement; check the details of access dates and author lists against NLM's samples. Our Vancouver guide covers that style on its own terms, and AMA is the third of the numbered medical styles you are likely to be asked for.

Outside biomedicine, the life sciences more often use CSE, the Council of Science Editors style, which offers three systems rather than one: citation-sequence, citation-name and name-year.

Sources Checked

Patrias K. Citing medicine: the NLM style guide for authors, editors, and publishers [Internet]. 2nd ed. Wendling DL, technical editor. Bethesda (MD): National Library of Medicine (US); 2007- [updated 2015 Oct 2; cited 2026 Sep 22]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK7256/ — reproduced here as NLM's own suggested citation. Chapter 5 (Dissertations and Theses) and chapter 24 (Databases/Retrieval Systems/Datasets on the Internet) were read via Internet Archive snapshots, because NCBI blocks automated requests.
National Library of Medicine. Samples of Formatted References for Authors of Journal Articles [Internet]. Bethesda (MD): NLM. Available from: https://www.nlm.nih.gov/bsd/uniform_requirements.html
International Committee of Medical Journal Editors. Recommendations: Preparing for Submission. Available from: https://www.icmje.org/recommendations/browse/manuscript-preparation/preparing-for-submission.html
Medical University of South Carolina Libraries. National Library of Medicine (NLM) Citation Style. Available from: https://musc.libguides.com/NLM
Middlebury College Library. NLM Citation & Style Guide. Available from: https://middlebury.libguides.com/citation/nlm

Wonders searches OpenAlex and Semantic Scholar and exports references in APA, MLA, Chicago, Harvard, IEEE and Vancouver, or as BibTeX, RIS or CSV — Vancouver being the closest of the six to an NLM reference list.