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National Library of Medicine (NLM) Citation Style

In-Text Citations

Within the text of a publication, individual references are presented in an abbreviated format that refers back to the list. These abbreviated references within the text are called in-text references.

Note that Citing Medicine does not recommend a particular style of in-text citations. Therefore, you may choose from the following three styles:

  • Citation-sequence: Numbers refers to items in reference list.
    • For the reference list, references are numbered in the list in the order they first appear in the text.
    • For example, if a reference by Waters is the first one referred to in the text, then the Waters reference is number one in the list.
      • "...reference to Waters article1".
  • Citation-Name Sequence: Numbers refers to items in reference list.
    • For the reference list, the references in the list are numbered in alphabetical order by author.
    • For example, a reference authored by Adam would be number 1, by Baker number 2, etc.
    • "...reference to Waters article15".
    • These numbers are used in the text regardless of the order in which they appear.
  • Name-year: Parenthetical statement including author last name and publication year.
    • In-text references consist of the surname of the author and the year of publication, enclosed in parentheses. 
    • For the reference list, the references are ordered first by author, then by year.
    • For example, “…reference to Brennan article. (Brennan 2020)”.

Both the citation-sequence and citation-name systems format parts of references in the same order that they are found in Citing Medicine. In the name-year system the date of publication is taken out of order and placed after the author or after the title if there is no author. 

Citation-Sequence: This system uses numbers within the text to refer to items in the end reference list. Number the references 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.

  • For the reference list, references are numbered in the list in the order they first appear in the text.
  • For example, if a reference by Waters is the first one referred to in the text, then the Waters reference is number one in the list.
  • "...reference to Waters article1".

Example (one in-text reference):

Chocolate has many potential health benefits such as improved blood flow1 and cognitive function 2.

Example (reference list):

1. ​Sokolov AN, Pavlova MA, Klosterhalfen S, Enck P. Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behavior. Neurosci Biobehav Rev [Internet]. 2013 Dec [cited 2020 June 15];37(10 Pt 2):2445-53. Available from: https://pubmed.ncbi.nlm.nih.gov/23810791

2. Scholey A, Owen L. Effects of chocolate on cognitive function and mood: a systematic review. Nutr Rev [Internet]. 2013 Oct [cited 2020 June 15];71(10):665-81. Available from: https://pubmed.ncbi.nlm.nih.gov/24117885

​When citing multiple references:

  • Separate numbers not in a continuous numeric sequence 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:

Chocolate has many potential health benefits such as improved blood flow1, mood 2-3 and brain function4-7 .

Chocolate has been shown 1,2,5,7,11-15 to lead to optimism.

Citation-Name Sequence: This system uses numbers within the text to refer to items in the end reference list. 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.

  • For the reference list, the references in the list are numbered in alphabetical order by author.
  • For example, a reference authored by Adam would be number 1, by Baker number 2, by Canter number 3, etc.
  • "...reference to Waters article15".
  • These numbers are used in the text regardless of the order in which they appear.

Example (one in-text reference):

Chocolate has many potential health benefits such as improved blood flow 11 and cognitive function 10.

Example (reference list):

10. Scholey A, Owen L. Effects of chocolate on cognitive function and mood: a systematic review. Nutr Rev [Internet]. 2013 Oct [cited 2020 June 15];71(10):665-81. Available from: https://pubmed.ncbi.nlm.nih.gov/24117885

11. ​Sokolov AN, Pavlova MA, Klosterhalfen S, Enck P. Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behavior. Neurosci Biobehav Rev [Internet]. 2013 Dec [cited 2020 June 15];37(10 Pt 2):2445-53. Available from: https://pubmed.ncbi.nlm.nih.gov/23810791

​When citing multiple references:

  • Separate numbers not in a continuous numeric sequence 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:

Chocolate has many potential health benefits such as improved blood flow 11, mood 1-2 and brain function 7-10.

Chocolate has been shown 2,,8,21-24 to lead to optimism.

Name-Year: Parenthetical statement including author last name and publication year.

  • In-text references consist of the surname of the author and the year of publication, enclosed in parentheses. 
  • For the reference list, the references are ordered first by author, then by year.

Example (in-text reference):

Chocolate has many potential health benefits such as improved blood flow (Sokolov 2013) and cognitive function (Scholey 2013).

Example (reference list):

Scholey A, Owen L. Effects of chocolate on cognitive function and mood: a systematic review. Nutr Rev [Internet]. 2013 Oct [cited 2020 June 15];71(10):665-81. Available from: https://pubmed.ncbi.nlm.nih.gov/24117885

Sokolov AN, Pavlova MA, Klosterhalfen S, Enck P. Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behavior. Neurosci Biobehav Rev [Internet]. 2013 Dec [cited 2020 June 15];37(10 Pt 2):2445-53. Available from: https://pubmed.ncbi.nlm.nih.gov/23810791