https://alternativeto.net/software/microsoft-academic/
https://www.semanticscholar.org/
http://www.harzing.com/pop_win.htm
https://scinapse.io/
http://www.sparrho.com/
http://www.scopus.com/
http://lens.org/
https://www.aminer.org/
http://www.arxiv-sanity.com/
http://webofknowledge.com/
https://unpaywall.org/welcome
