Grubb, P. (2005). "Order Perissodactyla". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3a eld.). Johns Hopkins University Press. pp. 633–634. ISBN 978-0-8018-8221-0. OCLC 62265494. [1] Alirita la 25an de Januaro 2017.