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
Thallium compounds have been used as rodenticides for many years. Reports of poisoning of domestic animals by thallium were published as early as 1920. The general use of these compounds by pest control companies, and their availability to the general public has increased the frequency of accidental poisoning of domestic animals.
Marshall, Virginia L.
"Thallium Poisoning in the Dog,"
Iowa State University Veterinarian: Vol. 27
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol27/iss3/4