When working on a large research project, it may be helpful to use a citation management system such as Zotero (available on the web). For smaller projects, it is often quicker to learn how to compose an accurate citation without using a citation generator, such as EasyBib, BibMe, Citation Machine, etc.
You can find citation style guides on the first floor of the library in the Reference Collection area.
Purdue Owl also has a useful and easy to understand guide for research and citation resources. The guide includes descriptions and examples on citing sources in MLA, APA, Chicago, and several other styles.