A comparison of calling patterns of purple-faced leaf monkeys (Trachypithecus vetulus vetulus and Tv nestor) in Sri Lanka's Wet Zone
C. Eschmann, K. Nekaris, P.H. Douglas, L. Birkett, A. Gunawardene, in: Folia Primatologica, Walter de Gruyter GmbH, 2008, pp. 305–401.