Citation Guide (HBS)This excellent guide in .PDF from the Harvard Business School covers citation within text as well as how to do a bibliography using Chicago style.
Citation MachineA site designed to help create bibliographies easily, this was developed by David Warlick & The Landmark Project.
Citing Sources Within Your PaperDuke University is responsible for this well-organized site about citing in the body of your text.
Copyright and CitationThis Boston University research guide offers links to information about copyright, public domain sites, citing sources and plagiarism.
Documentation StylesSimmons College has produced this guide that includes MLA, APA, AMA, ASA, CSE, and Chicago styles.
Documenting Electronic SourcesFrom the Purdue University Online Writing Lab (OWL), this site is a good place to start for MLA or APA styles.
EasyBib.comThis company has partnered with WorldCat, and can format, alphabetize and print a bibliography based on APA, MLA, or Chicago styles.
Online!Bedford/St. Martins published this reference guide to using Internet resources in print, but makes its chapters on citing resources available on the web. Included at this site are chapters on MLA, APA, and Chicago styles.
In addition to the four styles listed on this page, this work also includes style samples for ACS (for chemistry), Bluebook and ALWD (for legal), and others.