Do you have an unusual source to document?
Here are a few links that might help:
How do I cite a conference paper or convention proceedings?
How do I cite a YouTube video?
How do I cite a Test database?
How do I cite a musical score?
How do I cite a journal article that isn't published yet?
How do I cite Facebook and Twitter in general?
How do I create a reference and in-text citation for Facebook and Twitter?
How do I cite a Facebook fan page or profile information?
How do I handle an author who has a suffix like Jr or III?
How do I cite an online book (google books)?
Here is an example:
Seton, E. T. (1911). The Arctic prairies: A canoe-journey of 2,000 miles in search of
the caribou. New York: C. Scribner's Sons. Retrieved March 20, 2008, from Google Books: http://www.google.com/books?id=oyw6jc6kNgYC&printsec=frontcover&dq=arctic+prairies&ei=Z43iR5HeJ4qMiQGxjOHVBA