Spickett, Arthur M.; Burger, D.B.; Crause, J.C.; Roux, Elizabeth M.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)
Stenson, M.O.; Van der Merwe, J.S.; Vorster, R.J.; Viljoen, P.G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999)