Kozlov, V.A. & Malyshkina, T.P. (1999)
(Cretaceous Elasmobranchii of the genus Ptychodus from the Western Kazakhstan) «in russian». Materialy po Stratigrafii i Paleontologii Urala, 2, 232–238
Guinot, G. & Condamine, F.L. (2023)
Global impact and selectivity of the Cretaceous-Paleogene mass extinction among sharks, skates, and rays. Science, 379, 802–806
DOI: 10.1126/science.abn2080