American Medical Association (AMA) Style Quick Guide

• Place the reference number after the first mention of the material from the published study, and that means at the end of or within the first sentence with reference to the research. Many students place the reference number at the end of the paragraph or at the end of a subsequent sentence and this is not where it belongs.
• The superscript number should be outside of periods and commas and inside colons and semicolons. If there are two or more sources you want to cite at the same time, separate with a comma.  If it is a sequential series, you can separate with a hyphen. 
• Below are some examples from the 11th edition, 3.6. 
  • As reported previously,^1,3-8,19
  • The derived data were as follows^3,4: 
• Avoid putting superscript number after another number. 
  • Instead of: The 2 largest studies to date included 26² and 18³ patients. 
    • Use: The 2 largest studies to date included 26 patients² and 18 patients³. 
    • Or use: The 2 larges studies^2,3 to date included 26 and 18 patients, respectively. 
• If you have referenced a research paper in a paragraph and are continuing to discuss the paper, you do not have to keep repeating the reference number after subsequent sentences as long as it is clear from the context that you are still talking about that same study. If you move on to discuss a different study and then come back to the already quoted study, you will likely have to repeat the reference to orient the reader to the reference that you are talking about.

Note: Many of the examples above came from the 11th edition of the AMA manual in sections 3.6. 

• When using author's names, the reference goes after the names and not at the end of the sentence. Example: Jones et al ¹ studied the effect of dietary protein quantity and quality on plasma amino acids in healthy, 3 month old infants. Not: Jones et al studied the effect of dietary protein quantity and quality on plasma amino acids in healthy, 3 month old infants ¹.
• If there is more than two authors, list both authors' surnames. If there is more than two authors use "et al," or "and coauthors," or "and colleagues." 
  • Example:
    • Doe and Davies¹
    • Doe et al¹
• Do not use the possessive form et al (et al's).
  • Example: 
    • Doe et al's data supports our findings. 
    • Change to: The data in the study by Doe et al¹ support our findings. 
• If the paper was authored by a group, then cite the group and do not skip it. 
  • Example: 
    • The World Health Organization² reported that misinformation has become an infodemic. 
• The first time you mention an author with an acronym, spell out the whole name with the acronym in parentheses. After the first mention then it is okay to use the acronym. 
  • Example:
    • In the study conducted by the National Institutes of Health (NIH)³, it was found that... 

Note: Many of the examples above came from the 11th edition of the AMA manual in sections 3.7.