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)
Wilkins, A.L.; Miles, Christopher O.; De Kock, W.T.; Erasmus, G.L.; Basson, A.T.; Kellerman, T. Stephanus(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)