Ramphastos ambiguus ambiguus - Black-mandibled Toucan

Chapman, F. M. 1924. Auk: 41(1): 17-29.
Criteria for the Determination of Subspecies in Systematic Ornithology

No Author Listed. 1945. Auk: 62(1): 152-169.
Recent Literature

No Author Listed. 1945. Auk: 62(3): 466-487.
Recent Literature

Parkes, K. C. 1970. Auk: 87(4): 635-649.
In Memoriam: Walter Edmond Clyde Todd

Snow, B. K. 1977. Auk: 94(4): 623-645.
Territorial Behavior and Courtship of the Male Three-Wattled Bellbird

Graves, G. R. 1985. Auk: 102(3): 556-579.
Elevational Correlates of Speciation and Intraspecific Geographic Variation in Plumage in Andean Forest Birds

Raikow, R. J., L. Bicanovsky and A. H. Bledsoe. 1988. Auk: 105(3): 446-451.
Forelimb Joint Mobility and the Evolution of Wing-Propelled Diving in Birds

Remsen, J. V., Jr., M. A. Hyde and A. Chapman. 1993. Condor: 95(1): 178-192.
The Diets of Neotropical Trogons, Motmots, Barbets and Toucans

No Author Listed. 1999. Auk: 116(1): 284-297.