Odendaal, M.W.; Pieterson, P.M.; De Vos, Valerius; Botha, A.D.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)
Bingham, J.; Jacobs, Jeanette Antonio; Jaftha, Julian Bernard(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1998)