Google Scholar - Google Scholar is a freely accessible web search engine that indexes the full text of scholarly...

WorldWideScience - WorldWideScience is an all in one global science gateway service that is accelerating the scientific discovery and progress with databases and portals.

Refseek - Refseek is a best in class academic search engine tool for students and researchers to extract the relevant information across the internet.

SemanticScholar - An academic search engine that utilizes artificial intelligence methods to provide highly relevant results and novel tools to filter them with ease.

Scopus - Scopus is a bibliographic database containing abstracts and citations for academic journal articles.

Scinapse - Scinapse is a free, nonprofit, Academic search engine for papers, serviced by Pluto Network.