The Official APA Style
The APA Style is a useful site to help you use proper APA (American Psychological Association) in your science fair paper.
The Purdue OWL - APA Format
Purdue Universities OWL (Online Writing Lab) is a useful site to help you use proper APA (American Psychological Association) in your science fair paper.
Bibme
Free resource that will generate APA citations for journals, websites, books, etc.