Olson, Storrs L. 1976. "Oligocene fossils bearing on the origins of the Todidae and the Momotidae (Aves: Coraciiformes)." in Collected papers in avian paleontology honoring the 90th birthday of Alexander Wetmore, edited by Olson, Storrs L., 111–119. Smithsonian Contributions to Paleobiology. Washington, D.C.: Smithsonian Institution Press.