There are many ways to reference - in fact, more than one hundred - and different professional and academic disciplines use different styles. Biology and geology, for example, use the Columbia style, while the MLA style is used in economics, and the Chicago style is the standard for political science.

The style of the American Psychological Association (APA) is used to reference in the social sciences, and also includes many business and management subjects.

The APA style is often also called the "Author/Date" style because it begins references with the name of a document's author and the date of its publication.