Rogers, K. C., T. A. Portillo, D. E. Smialek, D. G. Miles, T. W. Lehenbauer, and R. Smyth. “A Comparison of Two Mannheimia Haemolytica Vaccination Strategies in Freshly Weaned Southeastern Feedlot Heifers”. The Bovine Practitioner, vol. 43, no. 1, Dec. 2008, pp. 27-31, doi:10.21423/bovine-vol43no1p27-31.