The Eocene Zygodactyl Birds of North America (Aves: Piciformes)DOI: info:10.5479/si.00810266.27.101Smithsonian Institution Press101–110
Feduccia, Alan and Martin, Larry D. 1976. "The Eocene Zygodactyl Birds of North America (Aves: Piciformes)." In Collected papers in avian paleontology honoring the 90th birthday of Alexander Wetmore. 101–110. Washington, D.C.: Smithsonian Institution Press. In Smithsonian Contributions to Paleobiology, 27. https://doi.org/10.5479/si.00810266.27.101.