1. Observational Study of Behavior: Sampling Methods
2. Bloomsmith, M. A., Baker, K. C., Lambeth, S. P., Ross, S. K. & Schapiro, S. J. (2000). Is giving chimpanzees control over environmental enrichment a good idea? In The apes: Challenges for the 21st century, conference proceedings (pp. 88-89). Brookfield, IL: Chicago Zoological Society.
3. Fear reactions of domestic sheep confronted with either a human or a human-like model
4. On the Rutting Behavior of the Mountain Goat
5. Geist, V. (1971). Mountain sheep: A study of behavior and evolution. Chicago: University of Chicago Press.