ResearchWriter
ResearchWriter by ActiveScholar is a complete research writing management system designed exclusively for academics, by academics.ResearchWriter solves all organizing issues by allowing the scholar to capture, manage, outline, write, format, and make sense of the research information quickly and easily. http://www.activescholar.com/
Mendeley
Mendeley turns even the largest set of documents into a fully searchable, easy-to-manage library. Researchers can read and annotate content via desktop client, browser or mobile app. Citation and bibliography creation is easy with thousands of styles to choose from. https://www.mendeley.com/
Zotero
Zotero allows you to add content from your web browser to your personal library with a single click. https://www.zotero.org/