It's important to cite sources you used in your research for several reasons:
Sources: Citing sources: Overview and Scholarly Conversations and You
The MLA Style Center is the only authorized Web site on MLA style.
There are several different style manuals for how to prepare citations in a bibliography. This page has many links to the different citation styles.
Use a citation generator when you need to create a bibliography. These user-friendly, easy-to-use tools create individual citations that must be copied and pasted into a Word document. Be sure to proofread your citations for accuracy, completeness, and correct formatting. Although citation generators can be quite reliable, they are not error proof.
Citation Builder — automatically generates citations for print or online sources in MLA, APA, and Chicago
MLA, APA, Turabian, Chicago, etc. Some features require a free account. Upgrade for additional features.
Also works as a citation manager, and not just generator. Mendeley is a free reference manager for students and researchers. Make your own fully-searchable library in seconds, cite as you write, as well as read and annotate PDFs on any device.
Like Mendeley, Zotero is also a robust citation manager. Billed as a "personal research assistant", it's is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources.