An author should never cite a source that they have not seen. When citing, be sure to refer to the version of the document that you saw. For example, do not cite a journal article you read online as a journal article in print.
Across all source types, be sure to list authors in the order that they appear in the text and be sure to include all authors.
Use PubMed journal abbreviations. You can look up PubMed abbreviations in the NLM Catalog. If a journal abbreviation is not included in PubMed, follow abbreviation rules for journal abbreviation in Citing Medicine.
Do not use bold, underline or italic fonts.
NLM Style does allow for some number of variations. It is up to the user to remember to be consistent with these variations. For example, if you decide to use a full journal title rather than the abbreviation, be sure that you use the full journal title for all journal citations.
General Format for references:
Author AA, Author BB, Author CC. Title of article. Abbreviated Title of Journal. Date of Publication; volume(issue): pagination.
Author AA, Author BB, Author CC. Title of book. Edition. Place of Publication: Publisher; Date of Publication. pagination.
Author AA. Name of the Web Site [Medium]. Place of Publication: Publisher; Date of Publication [Date of Update/Revision]. Available from: URL.