Below is an introduction to some of the most popular referencing styles and links to examples of referencing guidance documents and tutorials for each of the referencing styles featured.
The University of Chicago Press publishes The Chicago Manual of Style.
There is also an online version, the Chicago Manual of Style Online which offers a free 30 day trial.
The Manual features a free Chicago-Style Citation Quick Guide which gives examples of how to cite a variety of references including books, book chapters, journal articles, newspapers, book reviews, theses and websites. It also features a comprehensive FAQ section.
There a lot of free Chicago style guides on the web including: