Loan, R.W., Tung, H.- tang and Payne, J.B. 1998. Comparative efficacy and duration of immunity of commercial Pasteurella haemolytica vaccines. The Bovine Practitioner. 1998, 32.1 (Jan. 1998), 18–21. DOI:https://doi.org/10.21423/bovine-vol1998no32.1p18-21.