“…In several case [14,17] in which, for example, the scientific productivity of an author is described by the number of publications, citations and H-index, it is important to understand their sources, because the same variables may take different values if they are obtained via Web of Science, Scopus, Google Scholar or other disciplinary databases. In literature, there are also some papers in which the journal coverages of the various fields of these databases are compared [2,16,35] . In the greater part of these cases, although exceptions are made for medical sciences and some hard sciences, none of these is thoroughly exhaustive or representative.…”