Lameira, Adriano R; Vries, Han; Hardus, Madeleine E; Hall, Cedric P A; Mitra-Setia, Tatang; Spruijt, Berry M; Kershenbaum, Arik; Sterck, Elisabeth H M; van Noordwijk, Maria; van Schaik, Carel; Wich, Serge A (2013). Predator guild does not influence orangutan alarm call rates and combinations. Behavioral Ecology and Sociobiology, 67(3):519-528.
van Schaik, C P; Isler, K (2012). Life-history evolution in primates. In: Mitani, J C; Call, J; Kappeler, P M; Palombit, R A; Silk, J B. The evolution of primate societies. Chicago and London: The University of Chicago Press, 220-244.