APA is the required citation style for research papers in psychology.
The authoritative reference source on correct/proper APA citation style is:
The Publication Manual of the APA (6th Edition)
Call number: Ref. BF76.7 .P83 2010
Library North 1st Floor
User Services Desk (Non-circulating)
Online, the American Psychological Association offers:
The Basics of APA Style (Tutorial)
Purdue University's Online Writing Lab (The OWL) offers a popular APA Formating & Style Guide.