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
Blackhead has probably caused more losses to the turkey industry in this country than any other single disease. First described by Cushman in 1893, it has since led to the abandonment of turkey growing in many sections of midwestern and eastern United States. No turkey disease has been more often described and discussed. The early researches of Salmon, Higgins, Smith, and Graybill paved the way for the later studies by Tyzzer, Pettger, Billings, Van Es and Olney, and others, which have proved that the disease can be prevented by proper attention to sanitary details to be mentioned later.
Lee, C. D.
"Infectious Enterohepatitis (Blackhead),"
Iowa State University Veterinarian: Vol. 2
, Article 2.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol2/iss3/2