Commonly used citation styles include the American Psychological Association (APA) style, Chicago Style, and the Modern Language Association (MLA) style, but there are many others as well. Always check with your professors to determine which citation style they want you use!
The rules of each style are detailed in print publications called style manuals that you can access at our library. However, there are a number of online guides that provide tips and examples that may prove useful to you as well, including Purdue's Online Writing Lab (OWL) for MLA, APA, and Chicago format.