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 Jan. 17, 1950, the ambulatory clinicians at Iowa State College were called to see a 2-year-old Shorthorn heifer with a history of having been dehorned about 18 months previously, but horn stubs had grown out on the right side of the poll since that time.
Crawford, Donald H.
"Unusual Bovine Horn Stubs,"
Iowa State University Veterinarian: Vol. 12
, Article 9.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol12/iss2/9