These are four popular styles of documentation.

• MLA (Modern Language Association) is used in literature and most of the humanities.
• The APA (American Psychological Association), which is generally used in the social sciences
• The CBE (Council of Biology Editors) is used in biology and many other sciences.
• The Chicago Manual of Style which actually has two styles it favors.

Most styles ask that references be listed on a page by themselves, alphabetically by author, and includes all the references you used to produce your report. This list is called References, Works Cited, Cited References, or References, depending on the style you have used. (The Chicago Manual of Style uses the titles Bibliography, Selected Bibliography, and Works Cited.)

The list for any given paper or report may include a variety of sources. A source is anything you draw information from, and in your report you should list every source you use.