An EPFL laboratory has developed Datashare Network, a decentralized search engine paired with a secure messaging system that allows investigative journalists to exchange information securely and anonymously.
Despite citation counts from Google Scholar (GS), Web of Science (WoS), and Scopus being
widely consulted by researchers and sometimes used in research evaluations, there is no recent
or systematic evidence about the differences between them. In response, this paper investigates
2,448,055 citations to 2,299 English-language highly-cited documents from 252 GS subject categories published in 2006, comparing GS, the WoS Core Collection, and Scopus
List of search_engines that you can use to look for books, journal articles and primary source material. Your Mileage May Vary when it comes to full-text however