Pangty, Kanchan, et al. “Preliminary Binary Ethylenimine (BEI) Inactivated Bovine Papillomavirus (BPV) Vaccine Trial Against Cutaneous Warts in Bull Calves: A Pathological Assessment”. Brazilian Journal of Veterinary Pathology, vol. 3, no. 2, Nov. 2010, pp. 105-10, https://doi.org/10.24070/bjvp.1983-0246.003019.