ASU Library Citation Style Manual. This is an excellent page containing links to many of the most popular citation style formats
For an automated service to help format your citations, try:Son of Citation Machinefrom the Landmark Project. It is very easy to use and accurate.
This is a very comprehensive web page from Duke University Libraries entitled: Assembling a List of Works Cited in Your Paper.
I particularly like it because it includes examples for both the major formats of citable materials and the respective style manual citations