Zotero is a browser addon that collects, manages, and cites research sources. It lives in your web browser where you do your work and it's free. Zotero allows you to attach PDFs, notes, and images to your citations, organize them into collections for different projects, and create bibliographies.
Zotero Quick Start Guide
Zotero developers have published a web-based guide.
This guide was created by Jason Puckett and licensed by Georgia State University Library under a Creative Commons Attribution-Noncommercial 3.0 United States License. It has been adapted by Suzanne Hinnefeld, Saint Mary's College, Notre Dame, Indiana, in January 2022.
Jason Puckett has given permission to reproduce any part of it for noncommercial purposes as long as credit is included.