Useful Links

MLA style: http://owl.english.purdue.edu/handouts/research/r_mla.html

APA style: http://owl.english.purdue.edu/handouts/research/r_apa.html

Harvard style: http://www.tvu.ac.uk/lrs/guides/harvard.html

Turabian / Chicago styles: http://depts.gallaudet.edu/englishworks/writing/turabianguide.html