APPLEGATE, S.P. & UYENO, T. (1968)
The first discovery of a fossil tooth belonging to the shark genus Heptranchias, with a new Pristiophorus spine, both from the Oligocene of Japan. Bulletin of the National Science Museum, Ser. C (Geol. & Paleont.), 11 (2): 195–200, 1 fig., pl. 1.