Sarah Blaffer Hrdy (1977).
251
Yukimaru Sugiyama (1967).
252
Frans de Waal (1982); Jane Goodall (1986).
253
Sarah Blaffer Hrdy (2000).
254
Carson Murray et al. (2007).
255
Takayoshi Kano (1992), p. 208.
256
Frans de Waal (1997); Amy Parish and Frans de Waal (2000).
257
Martin Daly and Margo Wilson (1988).
258
Stephen Beckerman et al. (1998).
259
Meredith Small (1989); Sarah Blaffer Hrdy (1999), p. 251.
260