Zotero ("zoh-TAIR-oh") is a free research tool that allows you to:

• Collect & organize citations
• Attach PDFs, notes, and images to your citations
• Cite sources within your paper/thesis
• Share Zotero libraries (folders)

It's easy to use, and best of all, it's free. Zotero works with Chrome, Firefox and Safari, which allows you to work directly from your web browser.  Learn more at Zotero.org.