A List of Search Engines for Resource Materials
www.refseek.com is an academic resource search engine.
More than a billion sources www.worldcat.org – search within 20,000 global libraries.
https://link.springer.com – access to more than 10 million scientific documents: books, articles,
www.bioline.org.br is a library of published bioscience journals
http://repec.org – Volunteers from 102 countries collected nearly 4 million publications
www.science.gov is a US government search engine for over 2200 scientific websites.
www.pdfdrive.com is the largest site to download free PDF books. Claim over 225 million titles.
www.base-search.net is one of the most powerful search engines for academic research texts. More than 100 million scientific articles 70% free
www.refseek.com– Academic Search Engine www.refseek.com