Miles, Christopher O.; Wilkins, A.L.; Erasmus, G.L.; Kellerman, T. Stephanus(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994)
Swan, Gerry E.; Schultz, R.A. (Rowena Anitra); Kellerman, T. Stephanus; Mulders, M.S.G.; Maartens, B.P.; Van der Walt, J.J.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1995)