Online collaborative writing, citing, hosting of data and publishing.

WorldCat is the world's largest network of library content and services.

Mendeley is a desktop and web program produced by Elsevier for managing and sharing research papers, discovering research data and collaborating online.

Read, annotate, and share PDFs and more.

Reference management and knowledge organization.

Perma.cc is simple, easy to use, and is built and supported by libraries.

Annotate the web, with anyone, anywhere.

Papers helps you collect and curate your research material.

Abstract and citation database.

A semantic, scientific, web-enabled PDF reader.