The Chicago Manual of Style presents two basic documentation systems, the humanities style (notes and bibliography) and the author-date system. Choosing between the two often depends on subject matter and nature of sources cited, as each system is favored by different groups of scholars.
The humanities style is preferred by many in literature, history, and the arts. This style presents bibliographic information in notes and, often, a bibliography. It accommodates a variety of sources, including esoteric ones less appropriate to the author-date system.
The more concise author-date system has long been used by those in the physical, natural, and social sciences. In this system, 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.
The University of Chicago Press
http://www.chicagomanualofstyle.org/home.html
Note: Examples in this guide are for the humanities style (i.e. notes and bibliography) of CMOS. For author-date system examples, please use the manual.
A DOI is a unique alphanumeric string that provides a persistent link to content online. Chicago style asks that you include a DOI for journal articles that have one.
This guide was created with thanks to the Librarians at University of South Carolina's Thomas Cooper Library.
The Chicago Manual of Style 17th ed. by 
The Chicago Manual of Style 16th ed. by 
A Manual for Writers of Research Papers, Theses, and Dissertations, Eighth Edition by The following are links to the ONLINE versions of these citation manuals.
A Manual for Writers of Research Papers, Theses, and Dissertations (published by the University of Chicago Press and often referred to simply as Turabian), is a style guide for writing and formatting research papers (such as the arrangement and punctuation of footnotes and bibliographies). The style described in this book is commonly known as Turabian style, after the book's original author, Kate L. Turabian.
Wikipedia contributors. "A Manual for Writers of Research Papers, Theses, and Dissertations." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 3 Jan. 2016. Web. 4 Feb. 2016.
The Chicago and Turabian styles are nearly identical.
Kate Turabian, the dissertation secretary at the University of Chicago for over 30 years, developed her guide for students and researchers writing papers, theses, and dissertations. Her manual is based on the University of Chicago Press's Manual of Style and departs from it in few places. "Turabian," as her guide is called, synthesizes the rules most important for students' papers and other scholarly research not intended for publication, and omits some of the publishing details and options that "Chicago" provides.
USC Upstate Library - Citation Documentation Philosophy
The USC Upstate Library supports student learning and information literacy. Therefore, the library offers tools and resources for students to create their own citations and make informed decisions about citation styles. The experience of creating citations offers students the opportunity to learn about the parts and elements of citations. The process of creating citations strengthens both decision making and critical thinking skills. The familiarity of citation principles is imperative when the accuracy of a citation comes into question. The library offers many print and online citation style resources. The library encourages students to consult these resources to create their own citations basing them on established guidelines.