http://animaldiversity.ummz.umich.edu/accounts/colobus/c._guereza -- Animal Diversity
http://www.chaffeezoo.org/zoo/animals/colobus.html -- Chaffee Zoo
http://www.selu.com/bio/PrimateGallery/PrimateWeek/Colobus/index.html -- Primate of the Week
http://www.zoo.org/ --Woodland Park Zoo
(source of the two picture links on the physical
description page.
http://www.wildsanctuary.com -- Wild Sanctuary
(who generously allowed the use of their colobus
vocalization file)
"Colobus Monkey." Encyclopedia Americana. Grolier Incorpporated, CO. 1987.