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
The International Veterinary Congress was held at Madrid, Spain, May 21-27, 1959. Over 2500 veterinarians from allover the world attended. The meeting was devoted to general assemblies and specialty groups. In the general assembly meetings there were simultaneous translations into four languages--English, French, German and Spanish. The members of the audience were equipped with earphones and could listen in on any one of the four languages.
Merchant, I. A.
"Veterinary Medicine in European Countries,"
Iowa State University Veterinarian: Vol. 22
, Article 7.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol22/iss1/7