* {{cite book | last=Prothero | first=Donald R. | last2=Schoch | first2=Robert M. | title=The Evolution of Perissodactyls | publisher=Clarendon Pr. [u.a.] | publication-place=New York, NY | date=1989 | isbn=978-0-19-506039-3}}
<ref name="a916">{{cite book | last=Prothero | first=Donald R. | last2=Schoch | first2=Robert M. | title=The Evolution of Perissodactyls | publisher=Clarendon Pr. [u.a.] | publication-place=New York, NY | date=1989 | isbn=978-0-19-506039-3 | page=}}</ref>