NLM Style: Citing Your Sources

Citing Medicine does not recommend a particular style of in-text citations. Three styles are mentioned (see table below).

Check with your instructor/editor or guidelines to see which is most appropriate for your project. Remember to be consistent with the in-text citation style you choose.

Need more information? Refer to Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers, p. 491-499.

This system uses numbers within the text to refer to items in the end reference list. Number the reference and order them within the list according to the order in which they appear in the text. Use the same number for all following in-text references to the same document.

Example

In-text reference:

Traumatic life events and posttraumatic stress disorder (PTSD) are endemic among American civilians ¹.

Reference list:

1. Kessler RC, Sonnega A, Bromet E, Hughes M, Nelson CB. Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995 Dec; 52(12):1048-1060.

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

Examples with multiple references

Modern scientific nomenclature really began with Linnaeus in botany ¹ , but other disciplines ^2,3 were not many years behind in developing various systems ^4-7 for nomenclature and symbolization.

…have been shown ^{1,2,5,7,11-15} to abrogate the requirement of T-cells…

This system uses numbers within the text to refer to items in the end reference list. Number the references in alphabetical order. Arrange references by the same author in order of most recent publication date. Use the same number for all following in-text references to the same document.

Example

In-text reference:

Traumatic life events and posttraumatic stress disorder (PTSD) are endemic among American civilians ²².

Reference list:

22. Kessler RC, Sonnega A, Bromet E, Hughes M, Nelson CB. Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995 Dec; 52(12):1048-1060.

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

Examples with multiple references

Modern scientific nomenclature really began with Linnaeus in botany ¹ , but other disciplines ^2,3 were not many years behind in developing various systems ^4-7 for nomenclature and symbolization.

…have been shown ^{1,2,5,7,11-15} to abrogate the requirement of T-cells…

This system uses in-text citations that include the surname of the author or authors and the document's year of publication. Encluse the name and the year in parentheses. 

Example

In text reference:

The NIH has called for a change in smallpox vaccination policy (Fauci 2002) that...

End Reference:

Fauci AS. Smallpox vacination policy--the need for dialogue. N Eng J Med. 2002 Apr 25; 346(17): 1319-1320.