AMA style has the following basic requirements for reference lists:

• Within the body of the text, references should be numbered consecutively with superscript arabic numerals
• At the end of the document, references should be listed in numerical order
• Two references should not be combined under a single reference number
• Abbreviate names of journals to the format listed in the NLM catalog (search for the journal by title to get the abbreviation)
• For 1-6 authors, list each author; for 7 or more authors, list the first 3 followed by “et al.” (without the quotation marks)