This guide is based on chapter 15 of The Chicago Manual of Style, 16th Ed. (Chicago, University of Chicago Press, 2010). The author-date system is recommended by Chicago for works in the physical, natural, and social sciences.
As in APA style, in this style the name of the author if followed directly by the publication date, both in the reference list and in the in-text citation.
Every time you use ideas, theories, research, or direct quotes of other authors, you have to cite their works. Therefore, whether paraphrasing a concept, quoting an author directly, or summarizing an idea that somehow influenced your work, you must give credit to the original source. This will help you avoiding plagiarism.
The sources that you use within your work must appear both in the text (In-text citations) and, with full details, at the end of your research paper (References or Works Cited) in alphabetical order.
Each source cited in the text must appear in the reference list, and each entry in the reference list must be cited in the text.
For a complete list of style rules, please consult the Chicago Manual.