References should be numbered consecutively in the order in which they are first mentioned in the text (not in alphabetic order). Identify references in text and tables in superscript format. References cited only in tables or figure legends should be numbered in accordance with the sequence established by the first identification in the text of the particular table or figure. Use the style of the examples below, which are based on the formats used by the NLM in Index Medicus. Use complete name of the journal for non-indexed journals. Avoid using abstracts as references. Information from manuscripts submitted but not accepted should be cited in the text as "unpublished observations" with written permission from the source. Avoid citing a "personal communication" unless it provides essential information not available from a public source, in which case the name of the person and date of communication should be cited in parentheses in the text.
The commonly cited types of references are shown here, for other types of references such as newspaper items please refer to ICMJE Guidelines ( or