Fouts, R. S., Fouts, D. H., Jensvold, M. L. A. et al. 1994. An enriching approach to captive chimpanzee care. In Touch 1(1), 1 & 4-8.

The social environment [which includes the care providers] is perhaps the most critical factor in chimpanzee well-being, more important even than designs of the living space.