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 practicing veterinarian confronted with infertility or sterility in cattle must be able to determine whether he is confronted with a herd or an individual cow problem. In order to accomplish this task, an accurate herd history plus a herd examination is imperative. Although there are other causes of herd infertility, infectious disease presents the greatest challenge to the practicing veterinarian, particularly from the standpoint of diagnosis.
Herrick, John B.
"Infectious Diseases As a Cause of Infertility,"
Iowa State University Veterinarian: Vol. 16
, Article 2.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol16/iss3/2