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
Leukemia has been recognized by the veterinary and medical profession for a number of years. However, its etiology has still remained obscure with many theories having been postulated. It has been proven to be of an infectious nature in fowl where a filterable virus has been established as the direct etiologic agent.
Wykoff, M. Henry
Iowa State University Veterinarian: Vol. 8
, Article 11.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol8/iss1/11