Proctor , J., N. Long, C. Biehler, J. Rhinehart, L. Strickland, and J. Smith. “Effect of Semen Collection Method on Semen Quality in Developing Bulls”. Clinical Theriogenology, vol. 11, no. 3, Sept. 2019, p. 437, https://clinicaltheriogenology.net/index.php/CT/article/view/10208.