  The main objective of this paper is to empirically test whether the
identification of highly-cited documents through Google Scholar is feasible and
reliable. To this end, we carried out a longitudinal analysis (1950 to 2013),
running a generic query (filtered only by year of publication) to minimise the
effects of academic search engine optimisation. This gave us a final sample of
64,000 documents (1,000 per year). The strong correlation between a document's
citations and its position in the search results (r= -0.67) led us to conclude
that Google Scholar is able to identify highly-cited papers effectively. This,
combined with Google Scholar's unique coverage (no restrictions on document
type and source), makes the academic search engine an invaluable tool for
bibliometric research relating to the identification of the most influential
scientific documents. We find evidence, however, that Google Scholar ranks
those documents whose language (or geographical web domain) matches with the
user's interface language higher than could be expected based on citations.
Nonetheless, this language effect and other factors related to the Google
Scholar's operation, i.e. the proper identification of versions and the date of
publication, only have an incidental impact. They do not compromise the ability
of Google Scholar to identify the highly-cited papers.
