Top 50 popular popular science search engines website

Symbolab.com
Citeseerx.ist.psu.edu
Worldwidescience.org
Science-advisor.net
Academic.research.microsoft.com
Hcr.stateofinnovation.thomsonreuters.com
Ojose.com
Pasteref.com
Pubpsych.eu
Scicurve.com
Thesciencedictionary.com
Scientillion.com