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
Recently the ambulatory clinic was called to the Veterinary Research Farm to castrate seven boars. Since the boars ranged in weight from 400 to 700 lbs., it was a good opportunity to demonstrate various methods of restraint. Four different methods were used.
Janss, Robert; Stream, Jack; and Young, Frank
"Methods of Restraint in Boar Castration,"
Iowa State University Veterinarian: Vol. 13
, Article 15.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol13/iss1/15