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
Polo has been developed in speed to a point where it is second only to ice hockey. It is one of the roughest sports and certainly the one requiring the most skill and training on the part of the player and his horse. As a consequence the sport has been limited in the past to those with the means to purchase well trained stock and able to devote sufficient time to practice. Collegiate team members playing on army or university mounts, and local teams of cowboys and farmers have played much polo, though of a lower class.
Van Tuyl, G. E. and Bonelli, W. G.
Iowa State University Veterinarian: Vol. 6
, Article 8.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol6/iss2/8