AMA Help (11th Edition)

References should be numbered consecutively with arabic numerals in the order in which they are cited in the text.  Unnumbered references, in the form of a resource or reading list, are rarely used in JAMA Network Journals.  When they are used, these references appear alphabetically, by the first author's last name, in a list separate from the specifically cited reference list.

When citing a previously used source, reuse the same superscript number.

Each reference should be cited in the text, tables, or figures in consecutive numerical order by means of superscript arabic numerals.  It is acceptable for a reference to be cited only in a figure, table or a box and not in the text if it is in sequence with references cited in the text.  For example, if Table 2 contains reference 13, which does not appear in the text, this is acceptable as long as the last reference cited (for the first time) before the first text citation of Table 2 is reference 12.

Use arabic superscript numerals outside periods and commas, inside colons and semicolons.  When more than two 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.

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.

The following example is taken from the AMA Manual of Style (AMA, 2020, pg.64).