I expect political science majors to follow the APSA Style Manual in my classes.  A copy of the Style Manual is in the Fall 1985 issue of PS:  Political Science and Politics.  Briefly below, I lay out some of the relevant information that you will need.  Please consult the Style Manual for more complete information. 

A citation usually includes the author's name and the publication year with no commas separating the two. 

e.g., (Fenno 1978)
If there are two or three authors, list the last names of all three authors.  If there are four or more authors, list the first author's last name and then follow it with et al.
e.g., (Jacobson and Kernell 1981)
(Campbell et al 1960)

When multiple citations are cited, list the citations in alphabetical order and separate them with semi-colons. 

e.g., (Fenno 1973; Mayhew 1974; Fiorina 1977)

If you are quoting from an author, include the last name, publication date, and then have a comma separate the page number(s) from the year.

e.g., Putnam (1993, 4-5) says, "   " [if you mention the author before the quote]
"   " (Putnam 1993, 4-5). [if the author is not mentioned in the text]

For references, students should conform to the following format. For books:  

e.g, Last name, First name. Publication Year. Title. Place of Publication: Publisher.
Wilson, James Q. 2000. Bureaucracy: What Government Agencies Do and Why They Do It. New York: Basic Books.

If there are multiple authors, follow the above format except the second, third, . . . authors are listed First Name Last Name. 

e.g, Davidson, Roger, and Walter J. Oleszek.  1998.  Congress and Its Members, 6th ed.  Washington, D.C.:  CQ Press. 

If the book is an edited volume, follow the above format but at the end of the list of authors place a comma followed by eds.

e.g, Dodd, Lawrence C., and Bruce I. Oppenheimer, eds. 1998.  Congress Reconsidered, 5th ed.  Washington, D.C.:  CQ Press. 

If you cite a chapter from a edited collection, follow this format. 

e.g., Last name, First name.  Publication year. "Chapter Title."  In Book title, ed. Editor(s).  Place of Publication.  Publisher.
Skowronek, Stephen.  2000.  "Presidential Leadership in Political Time." In The Presidency and the Political System, ed. Michael Nelson.  Washington, D.C.:  CQ Press.

Another common source of information these days is the internet.  For information on citing the web, please look at Laura Boyer's How to Cite Electronic Information.  

Please examine the Style Guide for further questions or additional information.