Van Roosmalen, M.G.M., Tomas van Roosmalen i Russell A. Mittermeier, 2002: A Taxonomic Review of the Titi Monkeys, Genus Callicebus Thomas 1903, with the Description of two New Species: Callicebus bernhardi and Callicebus stephennashi, from Brazilian Amazonia. A: Neotropical Primates 10, 1-52. [1]Arxivat 2011-10-01 a Wayback Machine.
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Van Roosmalen, M.G.M., Tomas van Roosmalen i Russell A. Mittermeier, 2002: A Taxonomic Review of the Titi Monkeys, Genus Callicebus Thomas 1903, with the Description of two New Species: Callicebus bernhardi and Callicebus stephennashi, from Brazilian Amazonia. A: Neotropical Primates 10, 1-52. [1]Arxivat 2011-10-01 a Wayback Machine.