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.

HARVARD 

The Harvard referencing style is an example of author-date referencing. The Harvard style is very common and is used across most subjects.  

With the Harvard system, when you cite someone else's work (by including a quotation or by paraphrasing their work), you need to include the author's last name and the date of publication in brackets after the citation in the body of your paper. The full reference to the work is then included in an alphabetic reference list or bibliography at the end of your paper. 

There is no definitive form of Harvard referencing as there is no organisation that sets standards for the style.

Introduction to the Harvard Author-Date Referencing Style by University of Sydney

APA (AMERICAN PSYCHOLOGICAL ASSOCIATION) 

The American Psychological Association publishes a style guide, the Publication Manual of the American Psychological Association, which is commonly used by writers, editors and students in the social science subjects.

APA Reference List Examples from Finger Lakes Community College

CHICAGO 

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.

Chicago Manual of Style Examples of Bibliographic Citations in Music