de la Torre, S. et al. 1999. Preliminary study of the effects of ecotourism and human traffic on the howling behavior of red howler monkeys, Alouatta seniculus, in Ecuadorian Amazonia. Neotropical Primates. 7, 3 (Sep. 1999), 84–86. DOI:https://doi.org/10.62015/np.1999.v7.431.