MLA Handbook (8th Edition) by 
MLA Style Manual and Guide to Scholarly Publishing (7th edition) by Additional information on MLA style may be found at these websites:
APA Style, 7th edition
APA Style, 6th edition. Use only if your instructor directs you to do so. Otherwise, use the 7th edition links above.
What's the difference? Some key changes from 6th to 7th edition APA.
Publication Manual of the American Psychological Association (7th Edition) by The Publication Manual of the American Psychological Association, Seventh Edition is the official source for APA Style. With millions of copies sold worldwide in multiple languages, it is the style manual of choice for writers, researchers, editors, students, and educators in the social and behavioral sciences, natural sciences, nursing, communications, education, business, engineering, and other fields. Known for its authoritative, easy-to-use reference and citation system, the Publication Manual also offers guidance on choosing the headings, tables, figures, language, and tone that will result in powerful, concise, and elegant scholarly communication. It guides users through the scholarly writing process--from the ethics of authorship to reporting research through publication. The seventh edition is an indispensable resource for students and professionals to achieve excellence in writing and make an impact with their work. The seventh edition has been thoroughly revised and updated to reflect best practices in scholarly writing and publishing. All formats are in full color, with a new tabbed spiral version Improved ease of navigation, with many additional numbered sections to help users quickly locate answers to their questions Resources for students on writing and formatting annotated bibliographies, response papers, and other paper types as well as guidelines on citing course materials Dedicated chapter for new users of APA Style covering paper elements and format, including sample papers for both professional authors and student writers New chapter on journal article reporting standards that includes updates to reporting standards for quantitative research and the first-ever qualitative and mixed methods reporting standards in APA Style New chapter on bias-free language guidelines for writing about people with respect and inclusivity in areas including age, disability, gender, participation in research, race and ethnicity, sexual orientation, socioeconomic status, and intersectionality More than 100 new reference examples covering periodicals, books, audiovisual media, social media, webpages and websites, and legal resources More than 40 new sample tables and figures Expanded guidance on ethical writing and publishing practices, including how to ensure the appropriate level of citation, avoid plagiarism and self-plagiarism, and navigate the publication process Guidelines that support accessibility for all users, including simplified reference, in-text citation, and heading formats as well as additional font optionsThe Chicago Manual of Style offers two very different methods of citation:
The Notes and Bibliography (Humanities) style is preferred by many in literature, history, and the arts. This style presents bibliographic information in notes and, often, a bibliography. More info.
The Author-Date system (click for examples) is used by those in the physical, natural, and social sciences.Sources are briefly cited in the text, usually in parentheses, by author’s last name and date of publication. The short citations are amplified in a list of references, where full bibliographic information is provided. More info.
The most recent print editions of Turabian's A Manual for Writers and The Chicago Manual of Style are kept at the 1st floor Reference Desk at Walker Library.
The Chicago Manual of Style, 16th edition. Chicago: Chicago University Press, 2010.
(Reference - Walker Library - 1st Floor 029 C43 2010)
Turabian, Kate L. A manual for writers of research papers, theses, and dissertations : Chicago style for students, 8th edition. Chicago: Chicago University Press, 2013.
(Reference - Walker Library - 1st Floor 378.2 T84m 2013)
