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Citation Help: NLM

A guide to citing and writing, with information on APA, MLA, Chicago Manual of Style, and NLM.

Citing Medicine: the NLM Style

NLM Citation Sequence System

Three major systems of in-text references are used by medical publishers: citation-sequence, citation-name, and name-year. This guide is based on the the citation-sequence system. In the citation-sequence system, numbers are used to refer to the list called “References” at the end of your paper. Number the reference and order them within the list according to the order in which they appear in the text. For example, if a reference by Sanders is the first one referred to in the text, then the Sanders reference is number one in the References list. Use the same number for all following in-text references to Sanders, number 1.

In-text reference:

Studies show that 6.4% to 11% of all dental hygienists are diagnosed with carpal tunnel syndrome.1

Reference list:

  1. Sanders MA, Turcotte CM. Strategies to reduce work-related musculoskeletal disorders int dental hygienists: two case studies. J Hand Ther. 2002 Oct-Dec [cited 2017 Oct 17];15(4):363-374. In: ScienceDirect [Internet]. Amsterdam: Elsevier. Available from:

Citing multiple references:

When multiple references occur, follow these guidelines:

  • Separate numbers not in a continuous numeric sequences by commas with no spaces
  • Continue more than two numbers in a continuous sequence with a hyphen or dash between the first and last numbers
  • If there are only two consecutive numbers, separate them with a comma with no spaces


Given the working frequency, duration, and force required during scaling and root planing, research indicates that power instruments are often easier to handle due to the instrument design.11,12

The most influential risk factor in diagnosing WMSD is the number of years that a dental hygienist has worked in a clinical practice as it is tied to the duration of strain on the muscles.13- 15

Journal Abbreviations

The NLM Style uses journal abbreviations in the citation rather than the full journal title. To find the journal abbreviation, use the NLM Catalog. For example, if you search the catalog for the Journal of the American Dental Association, you will find that the abbreviation is J Am Dent Assoc.

NLM Journal Abbreviations

NLM - Examples

General NLM Rules for Citations


  • The bibliography, or works cited page, is titled REFERENCES, in bold, at the top, center of the page.
  • Arrange citations in the order they are cited in the paper starting with “1”
  • Use single line spacing.
  • Use a single, page-width column (no indenting)
  • Place the REFERENCES page immediately after the last page of the text.

Reference list


  • List names in the order they appear in the text.
  • Enter the last name first, followed by the initials of first and middle name (if given).
  • Do not place a comma between the last name and initials.
  • Separate author names from each other with a comma and space.
  • Omit degrees, titles, and rank preceding or following a personal name.
  • If more than 3 authors, list the first 3 authors followed by a comma and "et al."
  • End author information with a period.

Example: Wenger NK, Sivarajan Froelicher E, Smith LK, et al. 

Book and Article Titles

  • Enter the title as it appears in the original document, in the original language.
  • Capitalize only the first word of a title, proper nouns, proper adjectives, acronyms, and initialisms.
  • Use a colon followed by a space to separate a title from a subtitle, unless another form of punctuation (such as a question  mark, period, or an exclamation point) is already present.
  • Follow non-English titles with a translation whenever possible; place the translation in square brackets.
  • End a title with a period unless a question mark or exclamation point already ends it.
  • Do not italicize.

Example: Making sense of the chest x-ray: a hands-on guide. 

Place of Publication and Publisher

  • Well known cities need no state, province, or country abbreviation. Lesser known cities should be followed with the two-letter abbreviation for the state or province or country enclosed within parenthesis.
  • If place of publication is unknown, note as: [place unknown]:.
  • End place information with a colon.
  • Record the name of the publisher as it appears in the publication, using whatever capitalization and punctuation is found there.
  • End publisher information with a semicolon.

Example: New York: Oxford University Press; 

Date of Publication

  • Include the year, month, and day of publication in that order.
  • Use English names for months and abbreviate them using the first three letters, such as Jan.
  • For books, give the year of publication and end date information with a period.
  • For journals, end date information with a semicolon unless there is no volume or, then end with a colon.

Example (book): 2005.

Example (journal): 2005 Jan;

Journal Titles

  • Enter a journal title in the original language.
  • Abbreviate journal titles.
  • Use the NLM Catalog to find the abbreviated journal title.
  • End the journal title with a period.
  • Do not italicize.

Example: J Res Med Sci. 

Volume/Issue Numbers in Journals

  • Do not follow volume number(s) with any punctuation unless there is no issue number or other subdivision to the volume, then follow with a colon.
  • Place issue information in parentheses.
  • End issue information with a colon.

Example: 20(4):

Pagination in Journals

  • Give the beginning and ending page numbers on which article appears.
  • DO NOT include the letter p when citing articles!
  • Abbreviate page numbers
  • If pages are discontinuous, note all pages.
  • End pagination information with a period.

Example: 100-7.

Example: 322-64, 383-8.

Online Sources

  • Use the word "Internet" in square brackets as the Type of Medium after the journal title and follow it with the date of publication.
  • Follow the date of publication with the date cited in square brackets.
  • Include volume and issue numbers if available.
  • If pages are not noted, calculate the length of the article using the best means possible using print pages, screens, paragraphs, or bytes ( [30 p.]. [about 7 screens]. [about 17 p.]. [45 paragraphs]).
  • Provide the URL preceded by Available from.