APA and MLA Style Guides
When writing a research paper, you must indicate exactly where you found the information you present. Your sources are listed in a "References" list. This list appears at the end of your paper and includes all the sources used in the research and writing of your paper. The list should be double-spaced and in alphabetical order by the authors’ last names (or by title when no author is given). Always consult your instructor to learn his/her specific requirements for citation.
Bibliographic formatting for the 15th edition of the Chicago Manual of Style.
MLA style also specifies guidelines for formatting manuscripts and using the English language in writing and also provides writers with a system for cross-referencing their sources--from their parenthetical references to their works cited page. This cross-referencing system allows readers to locate the publication information of source material.
Purdue University online Writing Lab. Resources for writing, anotating your works, and doing research online.