Perrett, T.; Wildman, B. K.; Abutarbush, S. M.; Pittman, T. J.; Jones, C. R.; Pollock, C. M.; Schunicht, O. C.; Guichon, P. T.; Jim, G. K.; Booker, C. W. A Comparison of Two Mannheimia Haemolytica Immunization Programs in Feedlot Calves at High Risk of Developing Undifferentiated Fever/Bovine Respiratory Disease. Bov. pract. 2008, 42, 64-75.