1. Adams KM (2007) Refinement in the literature: searching for environmental enrichment. AATEX 14, Special Issue, 302–312
2. Baker K (1997) Straw and forage material ameliorate abnormal behavior in adult chimpanzees. Zoo Biol 16:225–236
3. Blaney E, Wells D (2004) The influence of a camouflage net barrier on the behavior, welfare, and public perceptions of zoo-housed gorillas. Animal Welfare 13:111–118
4. Bloomsmith MA, Brent LY, Schapiro SJ (1991) Guidelines for developing and managing an environmental enrichment program for nonhuman primates. Lab Anim Sci 41:372–378
5. Bloomsmith MA, Lambeth SP (2000) Videotapes as enrichment for captive chimpanzees. Zoo Biol 6:541–551