Note: when I first built this page almost 25 years ago during my years of teaching in the university, it was difficult for students to find online guidance about how to cite sources. This page had a dozen or more links to helpful sites. Since that time, Internet search engines and other tools have put an increasing number of resources at our fingertips. Also, over time links become inoperative. As a result, this page is not being maintained, although dead links are being removed.
A tool that may be interesting is available at custom-writing.org with helps for citations in APA, Chicago, CSE, Harvard, MLA, and Vancouver.
Also, you may find the Academic Citation Resource Guide helpful.
Links to Helpful Citation Guides
Style Comparison Sheet