Botha, C.J. (Christoffel Jacobus); Van der Lugt, Jaco J.; Erasmus, G.L.; Kellerman, T. Stephanus; Schultz, R.A. (Rowena Anitra)(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1997)
Keet, D.F.; Kriek, N.P.J.; Zakrisson, G.; Meltzer, David George Anton(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1997)