Geys, J. F. 1979. Salenioid Echinoids from the Maastrichtian (Upper Cretaceous) of Belgium and The Netherlands. Paläontologische Zeitschrift 53, 296-322.
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Geys, J. F.
1979
Salenioid Echinoids from the Maastrichtian (Upper Cretaceous) of Belgium and The Netherlands