Hartstein, E.F. & Decina, L.E. (1986)
A new Severn Formation (Early Middle Maastrichtian, Late Cretaceous) locality in Prince Georges County, Maryland. The Mosasaur, 3, 87–96

Udovischenko, N.I. & Nessov, L.A. (1987)
Sravnenye kompleksov khryashchevykh ryb i drugikh pozovonochnykh paleogena Pritashkentshkikh. Biostratigrafia, Paleontologia Osadochnogo Chekhla Ukrainy, 1987, 167–174