Equidae
Animal Web: Equidae, Back from the Brink, International Museum of the Horse: Horse Breeds of, National Park Service: Assateague's Wild Hors, Przewalski Horse, Sable Island Horses, The Quagga Project, theBigZoo.com: Grevy's Zebra, University of Michigan Museum of Zoology, Wild Horses -- an American Romance
Rhinocerotidae
Black Rhinoceros - Ecobeetle, Black Rhinoceros - Endangered Species in the Wild, Black Rhinoceros - Lincoln Park Zoo, Greater Indian Rhinoceros - Animal Diversity, Greater Indian Rhinoceros - theBigZoo.com, SOS Rhino, White Rhino EEP, White Rhinoceros - theBigZoo.com, WWF - Rhinoceros
Animals with Odd-Numbered Hooves
Information, photos and videos of horses, zebra, rhinoceros and other odd-toed ungulates.
Ultimate Ungulate Page: Perissodactyla
Taxonomy of the order of horses, zebras, tapirs and rhinoceroses, with biological descriptions of many individual species.