This two-minute video from NC State University Libraries explains citations, citation styles, and how they are used in academic writing.
“Citation: A (Very) Brief Introduction” by NCSU Libraries is licensed under CC BY-NC-SA 3.0
The full text of the Chicago Manual of Style Online provides searchable recommendations on editorial/citation style and publishing practices used in the humanities and social sciences.
CMoS is currently on the 18th edition. The 17th edition is also available, if necessary.