Nichols, M. (1993). The great apes: Between two worlds. National Geographic Society.
Chicago-referens (17:e uppl.)Nichols, Michael. The Great Apes: Between Two Worlds. Washington, D.C: National Geographic Society, 1993.
MLA-referens (9:e uppl.)Nichols, Michael. The Great Apes: Between Two Worlds. National Geographic Society, 1993.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.