Bingham, J.; Jacobs, Jeanette Antonio; Jaftha, Julian Bernard(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1998)
Tice, G.A.; Bryson, N.R.; Stewart, C.G.; Du Plessis, B.; De Waal, D.T.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1998)