found: Work cat.: Pigs, peccaries, and hippos, c1993:p. 41 ("The hippos, family Hippopotamidae, are separated from all other suiformes in the superfamily Anthracotheroidea. All Holocene or Recent hippos belong to two genera, Hexaprotodon (Choeropsis) and Hippopotamus. Only one species of each of these is usually recognized, but three more species became extinct within the Holocene on Madagascar.")
found: Mammal species of the world, 1993:pp. 380-381 (Family Hippopotamidae. Two genera, Hexaprotodon and Hippopotamus)
found: Walker mam. world:v. 2, pp. 1185-1187 (Family Hippopotamidae, Hippopotamuses. "This family of two Recent genera, each with a single species, originally occurred in suitable habitat throughout Africa south of the Sahara, and all along the Nile River. The two genera, Hippopotamus and Choeropsis, differ greatly in size ...")
found: Corbet, G.B. A world list of mammalian species, 1991:p. 126 (Family Hippopotamidae, hippopotamuses)