There are many different "styles" you may choose from when citing sources. MLA (Modern Language Association), Chicago, and APA (American Psychological Association) are the three most common styles. Your professor will probably tell you which style is he or she would like you to use.
The following quick guides for citing your sources are from Diana Hacker's Research and Documentation Online.
Dinand Library also has recent editions of style manuals in the Main Reading Room. These manuals include more detailed information and examples.
If you need assistance with citations for legal documents or government publications, these guides will help.