Reference Types - Quick Guide
NLM : https://www.nlm.nih.gov/bsd/uniform_requirements.html
Details, including fuller citations and explanations, are in Citing Medicine. (Note Appendix F which covers how citations in MEDLINE/PubMed differ from the advice in Citing Medicine.) For datasets (Item 43 below) and software on the Internet (Item 44 below), simplified formats are also shown.