Effect of environmental enrichment on behavioral and endocrine aspects of a captive orangutan (Pongo pygmaeus) - Pizzutto, Cristiane Schilbach; Nichi, Marcilio; Sgai, Manuela Gonçalves Fraga Geronymo; Corrêa, Sandra Helena Ramiro; Viau, Priscila; Beresca, Ana Maria; Oliveira, Claudio Alvarenga de; Barnabe, Renato Campanarut; Guimarães, Marcelo Alcindo de Barros Vaz (Laboratory Primate Newsletter, 2008)