Comparison of Google Scholar, Web of Science and Scopus

The article: Martín-Martín, A., Orduna-Malea, E., Thelwall, M., & López-Cózar, E. D. (2018, August 15). Google Scholar, Web of Science, and Scopus: a systematic comparison of citations in 252 subject categories. https://doi.org/10.31235/osf.io/42nkm
was summarised by its authors in the LSE impact blog on December 3rd at
https://blogs.lse.ac.uk/impactofsocialsciences/2019/12/03/google-scholar-web-of-science-and-scopus-which-is-best-for-me/
The scholarly article ends by saying "In conclusion, the inclusive paradigm of document indexing popularised by Google Scholar facilitates discovery of not only the most well-known sources, but also of sectors of scholarly communication that were previously hidden from view." but it highlights the tradeoffs, as Google Scolar has issues of its own. Essentially I think the message is what you may well already know i.e. if you want a thourough search, search all 3 of them.