Google Scholar

Google Scholar is a freely accessible web search engine that indexes the full text of scholarly literature across an array of publishing formats and disciplines.

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ResearchGate

ResearchGate was built by scientists, for scientists. It started when two researchers discovered first-hand that collaborating with a friend or colleague on the other side of the world was no easy task.

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Microsoft Academic Search

Microsoft Academic Search is an experimental research service developed by Microsoft Research to explore how scholars, scientists, students, and practitioners find academic content, researchers, institutions, and activities.

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