Google Scholar - Google Scholar is a freely accessible web search engine that indexes the full text of scholarly...
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
Scinapse - Scinapse is a free, nonprofit, Academic search engine for papers, serviced by Pluto Network.
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.
SemanticScholar - An academic search engine that utilizes artificial intelligence methods to provide highly relevant results and novel tools to filter them with ease.
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .