AMA (11/e) Style Guide

Use superscript arabic numerals to cite material, e.g., 1    The first reference used in a written document is listed as 1 in the reference list.

Where to place the superscript? 

• The superscript number 1  is inserted into the document immediately next to the fact, idea, concept, or quotation being cited.  Example. This drug is used to treat hepatitis.1
• If citing directly (word for word), indicate it is a quote by using double quotation marks around the original phrase. The superscript then appears after the quotation mark. Example: "The basic ideas of a 'living-food' or 'raw food' diets are consuming all or primarily uncooked foods."4

• Outside periods and commas. Example: Storing latex at high heat may cause degradation, 2,3-5,7  but it is difficult to keep materials cool in a desert environment.
• Inside colons and semi-colons. Example: Some physicians choose to store prescription pads in locked cabinets 8; others keep them in their coats at all times. 9
• When more than 2 references are cited at a given place in the manuscript, use hyphens to join the first and last numbers of a closed series; use commas without space to separate other parts of a multiple citation.  Example: As reported previously,1,4-7,19,24
• Avoid placing a superscript reference citation immediately after a number or an abbreviated unit of measure to avoid any confusion between the superscript reference citation and an exponent. See Examples:

If a reference is used multiple times in one paper, use the same number throughout.

At the end of the document, include a reference list with full citations to each item. Name it References. Order citations as they appear in your paper.

You may use author names in your text, as long as these mentions are accompanied by numbered citations. Use last names only.  For items with one or two authors, include both names. For items with 3 or more authors, include the first author's surname and then 'et al' or 'and colleagues'.

Two author Example: 

• Smith and Jones² reported on the questionnaire.

More than two authors:

• Hammersmith et al³ reported on the survey.

The format for authors in in-text citations is different than what is required of listed references. In the list of references all authors should be given unless there are more than 6, in which case the names of the first 3 authors are used followed by “et al.