At Anne-Wil Harzing’s Publish or Perish:
When comparing Google Scholar and ISI citation scores, the Business academic has six times as many citations in Google Scholar than in ISI. However, this difference is dwarfed by the increases for the Political Scientist (15 times), the Cinema Studies Academic (25 times), the Linguist (32 times) and the Educationalist (33 times). It is clear that for academics working in the Social Sciences and Humanities, a focus on citations to ISI listed publications only, severely underestimates their citation impact.
With regard to the differences between Google Scholar and Scopus, the Social Science and Humanities academics again follow a different pattern from most of the Science academics. Whilst for the Science academics differences between Google Scholar and Scopus are slightly larger than between Google Scholar and ISI, for academics in the Social Sciences and Humanities, they are slightly smaller, but still substantial in absolute terms. Differences run from 3.5 times as many citations in Google Scholar for the Business academic to 27 times as many for the Linguist. The Cinema Studies academic shows a 180 times increase in citations, but that is caused entirely by the very incomplete coverage of her publications in Scopus.
People might find her Publish or Perish software useful for locating citations and calculated their own metrics.