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Kulkarni, A. V.; Aziz, B.; Shams, I.; Busse, J. W. (2009). "Comparisons of Citations in Web of Science, Scopus, and Google Scholar for Articles Published in General Medical Journals". JAMA. 302 (10): 1092–6. doi:10.1001/jama.2009.1307. PMID19738094.