Scholtz, M.M.; Spickett, Arthur M.; Lombard, P.E.; Enslin, C.B.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)
Odendaal, M.W.; Pieterson, P.M.; De Vos, Valerius; Botha, A.D.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)
Kellerman, T. Stephanus; Erasmus, G.L.; Brown, J.M.M.; Maartens, B.P.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)