†Calippus (Grammohippus) Hulbert 1988

Hulbert 1988. Calippus and Protohippus (Mammalia, Perissodactyla, Equidae) from the Miocene (Barstovian - Early Hemphillian) of the Gulf coastal plain. Bulletin of the Florida State Museum Biological Sciences, 32(3) 1988: 221-340