Minnaar, P.P.; McCrindle, Robert Ian; Naude, T.W.; Botha, C.J. (Christoffel Jacobus)(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000)
Swan, Gerry E.; Oliver, D.W.; Van Rensburg, J.; Steyn, H.S.; Mulders, M.S.G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000)