Zotero
Zotero (pronounced "zoh-TAIR-oh") is a free tool that helps you keep track of your research. You can create and store citations, include links, files and images, and create bibliographies - even annotated bibliographies. For the full features, download the full version, or use ZoteroBib to create bibliographies on the fly.
"Zotero is a lifesaver!" - a satisfied Cal Maritime senior.
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Zotero allows you to attach PDFs, notes and images to your citations, organize them into collections for different projects, and create bibliographies.