  Which studies, theories, and ideas have influenced Eugene Garfield's
scientific work? Recently, the method reference publication year spectroscopy
(RPYS) has been introduced, which can be used to answer this and related
questions. Since then, several studies have been published dealing with the
historical roots of research fields and scientists. The program CRExplorer
(http://www.crexplorer.net) was specifically developed for RPYS. In this study,
we use this program to investigate the historical roots of Eugene Garfield's
oeuvre.
