Academia.edu - Academia is a website where you can share papers that are written with other users. You can use a Google or Facebook account to sign in to the website.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
Google for Education - Google for Education takes the cast analytical knowledge of Google and transforms it into a platform that educators can use to better communicate with their students in innovative ways.
Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.
Crossref - Crossref makes research outputs easy to find, cite, link, assess, and reuse. We’re a not-for-profit membership organization that exists to make scholarly communications better.
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .