What about Google Scholar when searching information in Human and Physical Geography?

This study focuses on four bibliographic tools and aims to highlight what the use of the Google Scholar search engine can yield, in comparison with three commercial bibliographical databases: the well known multidisciplinary database Web of Science (WoS); GeoRef, a specialized data base in geosciences; and FRANCIS, which includes international geographical bibliography. To identify the bibliographic references published yearly between the years 2005 to 2009, ten keywords placed between quotation marks have been searched through the title field of the search tool interfaces. On a monthly basis, from November 2010 to July 2011, an identical process was repeated to get some information on the repeatability of the searches. Initially the whole set of results was analysed, and then the search results of two keywords were studied in more details.
The results indicate that GS provides a high overlap with the search results of the other databases, but also yields numerous unique hits. Moreover, it seems that it is also able to find diverse types of literature, while the others are more specialized.