APA style was developed by the American Psychological Association. The social sciences often use APA style for documenting sources.
Publication Manual of the American Psychological Association (7th ed.) by 
Scientific Style and Format (8th ed.) by CSE style was developed by the Council of Science Editors. It is often used in Biology and Kinesiology. For the Biology and Kinesiology Departments, please cite all articles using the print format - whether you are using the print or not. Do not include URLs, date accessed, names of databases, etc.
MLA was developed by the Modern Language Association. The humanities typically use MLA format to cite sources.
MLA Handbook (9th ed.) by Turabian style is named for its developer Kate Turabian, and is used in various disciplines, including history. This style is sometimes referred to as Chicago style since it is based on The Chicago Manual of Style.
A Manual for Writers of Research Papers, Theses, and Dissertations (9th ed.) by 
The Chicago Manual of Style (17th ed.) by 
Student's Guide to Writing College Papers by How to Cite your Sources in PowerPoint
PowerPoint Presentations need citations just as an essay or research paper needs a list of references you used for information.
Example of an APA PowePoint Presentation