Reference

Miranda Armour-Chelu, Raymond L. Bernor, Hans-Walter Mittmann (2006): Hooijer’s Hypodigm for "Hipparion" cf. ethiopicum (Equidae, Hipparioninae) from Olduvai, Tanzania and comparative Material from the East African Plio-Pleistocene – Beiträge zur Paläontologie – 30: 15 - 24.