Van Aswegen, G.; Kotze, Sanet H.; Van der Merwe, N.J.; Smith, G.A.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1992)
Kotze, Sanet H.; Van der Merwe, N.J.; Van Aswegen, G.; Smith, G.A.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1992)
Van der Walt, M.P.K.; Van Rooyen, J.M.; Oberholzer, G.; Van Aswegen, G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1992)