APA Style CENTRAL is the official online guide to APA Style. Use the "Learn" tab at the top of the page to access guides, tutorials, sample references, and official documentation from the APA Publication Manual.
This flowchart published by the APA can help you to decide when to use a DOI versus a URL in citations:
The official online version of the Chicago Manual of Style includes a searchable version of the manual's text as well as a Q&A section and Quick Guides. Suitable for both Notes and Bibliography and Author-Date styles.
"The Vancouver Style is the citation style used by most biomedical journals and many scientific journals. It is also known as the Uniform Requirements for Manuscripts Submitted to Biomedical Journals." - Vancouver Community College Library