Line, S. W., Clarke, A. S., Markowitz, H. 1987. Plasma cortisol of female rhesus monkeys in response to acute restraint. Laboratory Primate Newsletter 26(4), 1-3.

Confinement in a transfer box was a significant event, as measured by cortisol response, even though this condition was presumably intrinsically less stressful than manual restraint [with the help of the squeeze-back in the home cage]. .... Novelty alone can be a significant source of stress for laboratory primates.