Nelson, R. J., Mandrell, T. D. 2005. Enrichment and nonhuman primates: "First, do no harm". ILAR Journal 46(2), 171-177.
Since the 1998 publication of The Psychological Well-Being of Nonhuman Primates by the National Research Council, and the 1991 implementation of the 1985 Animal Welfare Act Amendment, many formal and informal nonhuman primate enrichment programs...