(Top) Graph illustrating citations in books for Plasmodium falciparum and Plasmodium vivax from 1900 to 2008, generated by use of the tool at http://books.google.com/ngrams. (Top) Graph illustrating citations in books for Plasmodium falciparum and Plasmodium vivax from 1900 to 2008, generated by use of the tool at http://books.google.com/ngrams. (Bottom) Citation data from PubMed since 1960. (Reproduced from reference174, which was published under a Creative Commons license.) J. Kevin Baird Clin. Microbiol. Rev. 2013; doi:10.1128/CMR.00074-12