Hippopotamus - Wikipedia
Hippopotamus | Size, Diet, Habitat, & Evolution | Britannica
Hippopotamus, facts and photos - National Geographic
Hippopotamus | Species | WWF - World Wildlife Fund
HIPPOPOTAMUS中文(简体)翻译:剑桥词典 - Cambridge Dictionary
Hippopotamus - Simple English Wikipedia, the free encyclopedia
Hippopotamidae - Wikipedia
Hippopotamus - National Geographic Kids
Characteristics and behavior of the hippopotamus | Britannica
Hippopotamuses: Hippopotamidae - Encyclopedia.com