Zotero is free "bibliographic citation management" software that allows you to save, collect, manage, cite, and share research sources. Zotero works inside your browser (it works best in Firefox and Chrome, though there is a version Safari), enabling you to easily save citations as you do research. You can also take notes in Zotero, allowing you to store your reactions to a source right next to its citation. Use the Zotero word processor plugins to easily cite your sources and create a bibliography while you work. (NOTE: Though Zotero will save you lots of time in the creation of footnotes/in-text citations and bibliographies, it's always a good idea to proofread your work.)