Check with instructor on the preferred style he or she wishes you to use and be sure to conslult the most up-to-date edition of that style manual.
Simple free online source.
Free open source online citation tool, easier to use than RefWorks. Zotero works with Firefox for Windows, Mac and Linux but not Internet Explorer (IE) or Google Chrome.
Which should you use?
Ask each of your professors which style they want you to use. If they have no preference you can follow and of these style, although most of our Seminary students are asked to use either the MLA or Turabian Style Manuals.
Print versions of these style manuals contain examples of citing more sources than these web pages do, as well as other things you may need to know, such as margins, font size, etc.
I like the "Long Island University Library Guide" as it is "COLOR CODED"