Author variations apply to all reference types (books, journal articles, reports etc.). Author surnames (family names) are followed by their two-letter initials with no space or full stop between the initials, e.g. Smith JA. Commas are used to separate each author's name, e.g. Khan FM, Gibbons JP.
Journal titles are abbreviated in the Vancouver style, e.g. New England Journal of Medicine appears as N Engl J Med in the reference list entry. A list of abbreviations is available through PubMed at: https://pubmed.ncbi.nlm.nih.gov/. Click on Journals (under Explore) and enter the full journal title to view its abbreviation. Alternative sources of journal title abbreviations are listed in appendix B of Citing Medicine.