Van Aswegen, G.; De Vos, Valerius; Schoeman, J.H.; Van Noorden, Susan; Kotze, Sanet H.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)
Bezuidenhout, A.J. (Abraham Johannes), 1942-; Seegers, Christine D.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)