Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
On November 10, 1938, a purebred Percheron filly, seven months of age, owned by S. S. Hansen of Nevada, Iowa, was presented at the Iowa State College Veterinary Clinic for examination. This colt possessed two fully and equally developed hoofs on the right front foot.
Telleen, C. L.
"Colt Born With Bovine Foot,"
Iowa State University Veterinarian: Vol. 1
, Article 6.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol1/iss1/6