Which citation style to use depends on the discipline of your course and professor for whom you are writing.
The Online Writing Lab (OWL) at Purdue provides great overviews of the three most common citation styles: APA, MLA, and Chicago.
There also are many citation helpers on the internet. Remember, when you are using a citation builder you should always double check the format of the citation before including it in the final version of your paper - they may be machines but they are not always perfect!
The Librarians are here to help if you still have questions!
