APA-referens (7:e uppl.)

Waal, F. B. M. d. (2002). Tree of origin: What primate behavior can tell us about human social evolution (1st Harvard University Press pbk. ed.). Harvard University Press.

Chicago-referens (17:e uppl.)

Waal, F. B. M. de. Tree of Origin: What Primate Behavior Can Tell Us About Human Social Evolution. 1st Harvard University Press pbk. ed. Cambridge, Mass.: Harvard University Press, 2002.

MLA-referens (9:e uppl.)

Waal, F. B. M. de. Tree of Origin: What Primate Behavior Can Tell Us About Human Social Evolution. 1st Harvard University Press pbk. ed. Harvard University Press, 2002.