W. Jens

Excretion patterns of solute and different-sized particle passage markers in foregut-fermenting proboscis monkey (Nasalis larvatus) do not indicate an adaptation for rumination

M. Kreuzer, M. Clauss, John C. M. Sha, 2015, Physiology & Behavior.

Differences in Subadult Behaviors of Chimpanzees Living in Peer Groups and in a Family Group

J. Van Hooff, H. Dienske, R. Spijkerman, 1997, International Journal of Primatology.

Differences in Variability, Interactivity and Skills in Social Play of Young Chimpanzees Living in Peer Groups and in a Large Family Zoo Group

J. V. Hooff, H. Dienske, R. Spijkerman, 1996 .

Causes of Body Rocking in Chimpanzees (Pan Troglodytes)

J. Van Hooff, H. Dienske, R. Spijkerman, 1994, Animal Welfare.