T. Matys Grygar belongs among 100 thousand most cited scientists (out of ca. 6,600 thousand) according to bibliometric analysis published in PLoS journal. The analysis considered relative citation rates in individual disciplines, in which the scientists have published, Geochemistry & Geophysics, Palaeontology, and Earth & Environmental Sciences in the case of T. Matys Grygar. The reason for T. Matys Grygar position in the list has been his work in several scientific disciplines during his career.
Ioannidis JPA, Baas J, Klavans R, Boyack KW (2019) A standardized citation metrics author database annotated for scientific field. PLoS Biol 17(8): e3000384 (https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000384&rev=2)