PEARSSON, E. L., DAVIS, J. M. & LITCHFIELD, C. A. (2010) – zootier-lexikon.org https://www.zootier-lexikon.org/index.php?option=com_k2&view=item&id=6919%3Apearsson-e-l-davis-j-m-litchfield-c-a-2010
A Case Study of Orangutan and Siamang Behavior Within a Mixed-Species Zoo Exhibit. Journal of Applied Animal Welfare Science, 13:4, 330-346, DOI: 10.1…
able to interact peacefully, there is an inherent danger