Many disciplines use MLA style, the citation style developed by the Modern Language Association. Some disciplines require other citation styles such as the Turabian, Chicago, or APA (American Psychological Association) styles.
Always ask your professor which style is preferred in his or her class. There are printed style guides at the Reference Desk. Purdue OWL is a great source to reference. The University Writing Center can help too.
 Joseph Gibaldi, MLA Handbook for Writers of Research Papers, 6th ed. (New York: Modern Language Association, 2003).
 Kate L. Turabian, A Manual for Writers of Term Papers, Theses, and Dissertations, 6th ed. (Chicago: University of Chicago Press, 1996).
 The Chicago Manual of Style, 15th ed. (Chicago: University of Chicago Press, 2003).
 Concise Rules of APA Style (Washington, D.C.: American Psychological Association, 2005).