The following web documents provide examples on how to cite sources using APA, MLA and other style guidelines. For complete information, always refer to the latest published manuals. 

General Writing Source 
OWL (The Purdue Online Writing Lab)

Specific Style Guides
APA Style Guide (OSU): html  pdf
MLA Style Guide (OSU): html  pdf

AMA Style Guide
CSE Style Guide (OSU): html 
Chicago Manual of Style (OSU): html  pdf  
NLM Style Guide
Turabian Style Guide (OSU): html  pdf 

Other Web Sources
APA Style Help (American Psychological Assoc.)
Bowling Green State University (Jerome Library): MLA (pdf) and APA (pdf) 
Citing Resources (Youngstown State University)