APA

• Citation Machine - from The Landmark Project and David Warlick. A great and fast way to put your citation information into the correct format for both APA and MLA.
  
• Purdue's APA format - 5th edition by Purdue University Online Writing Lab
  
• The Writing Center - @ the University of Wisconsin - Madison
  

ASA

• Purdue's ASA format: Brought to you by the Purdue University Online Writing Lab
• Cal State University Library ASA style guide

MLA

• Citation Machine - from The Landmark Project and David Warlick. A great and fast way to put your citation information into the correct format for both APA and MLA.
  
• The Writing Center - @ the University of Wisconsin - Madison
  

OTHER

• The Writing Center - @ the University of Wisconsin - Madison