Google Scholar: not reliable for citations counting
According this study related to Social Sciences publications, Google Scholar provides “vastly larger citation counts than either Scopus or Web of Science when all results are taken into account, but only slightly larger counts when only scholarly journals are considered“….
The study also deals with citation counting issue, saying that “ it is relatively easy to falsify citing references to research and create “search engine spam” which artificially inflates citation countswithin Google Scholar. While it is unclear as to whether this is occurring deliberately and if so, towhat extent, it remains an issue which should engender cautious use of search engine citation data“.
As a conclusion the study says that “ Google Scholar may not be as reliable as either Scopus or Web of Science as a stand-alone source for citation data“
Elaine M. Lasda Bergman. Finding Citations to Social Work Literature: The Relative Benefits of Using Web of Science, Scopus, or Google Scholar. The Journal of Academic Librarianship, Available online 23 October 2012