Behringer, V., Stevens, J. M. G., Hohmann, G., Möstl, E., Selzer, D., & Deschner, T. (2014). Testing the Effect of Medical Positive Reinforcement Training on Salivary Cortisol Levels in Bonobos and Orangutans. Public Library of Science.

Behringer, Verena, Jeroen M. G. Stevens, Gottfried Hohmann, Erich Möstl, Dieter Selzer, i Tobias Deschner. Testing the Effect of Medical Positive Reinforcement Training On Salivary Cortisol Levels in Bonobos and Orangutans. Public Library of Science, 2014.

Behringer, Verena, et al. Testing the Effect of Medical Positive Reinforcement Training On Salivary Cortisol Levels in Bonobos and Orangutans. Public Library of Science, 2014.