Kellerman, T. Stephanus; Maartens, B.P.; Schultz, R.A. (Rowena Anitra); Swart, D. Petro(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994)
Odendaal, M.W.; De Cramer, Kurt Guido Mireille; Van der Walt, Martha L.; Botha, A.D.; Pieterson, P.M.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994)