Odendaal, M.W.; De Cramer, Kurt Guido Mireille; Van der Walt, Martha L.; Botha, A.D.; Pieterson, P.M.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994)
Van Aswegen, G.; Schoeman, J.H.; De Vos, Valerius; Van Noorden, Susan(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994)