MacGregor, S., D. Smith, L. J. Perino, and B. D. Hunsaker. “An Evaluation of the Effectiveness of a Commercial Mannheimia (Pasteurella) Haemolytica Vaccine in a Commercial Feedlot”. The Bovine Practitioner, vol. 37, no. 1, Feb. 2003, pp. 78-82, doi:10.21423/bovine-vol37no1p78-82.