The Chicago Manual of Style is a style guide for American English published since 1906 by the University of Chicago Press. It presents citations and references in 2 variations:
the Notes-Bibliography System, used in literature, history, and the arts
the Author-Date System,used in the social/sciences
In addition, many professors refer to Kate L. Turabian's Manual for Writers of Research Papers, Theses, and Dissertations (8th ed.). It follows the two CMS patterns of documentation with some changes specifically for student papers.
Text should be double-spaced, with the following exceptions:
Subheadings should be used for longer papers per the following 5 levels: