Vorlage:Williamson et al., 1993

• Williamson, T.E., Kirkland, J.I. & Lucas, S.G. 1993. Selachians from the Greenhorn Cyclothem (“Middle” Cretaceous: Cenomanian-Turonian), Black Mesa, Arizona, and the paleogeographic distribution of Late Cretaceous selachians. Journal of Paleontology, 67: 447–474.