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
Bubbles, a one-hundred and twenty-five pound California sealion, has performed eight times daily during the Black Hills tourist season for the past seven years with but one mistake; on September 15, 1969, instead of catching and throwing his ball back to the trainer and to the other seals, he caught and swallowed it.
"Gastric Foreign Body Removal in a Seal,"
Iowa State University Veterinarian: Vol. 31
, Article 2.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol31/iss3/2