Just in case you are writing a research paper next term ~Who isn't?
Above is a link that will create citations in APA, MLA, and many other styles
If you are referencing a website, all you have to do is enter the URL and a citation is automatically generated. WIth a book, you simply enter the ISBN number. The site will create an alphabetized bibliography as well.
I've been using mendeley.com to track PDF references.however, this site looks easier for websites and books. Nice to know.