Chicago Manual of Style, 17th ed.
The Chicago Manual of Style (CMS) covers both the Notes-Bibliography System (NB), used primarily in the humanities and the Author-Date System (AD), used primarily in the social sciences. As of 2015, the AD System replaces the American Anthropological Association’s AAA Style Guide.
It’s available full text online here.
Purdue University’s useful OWL citation quick guide is available here.