Mohan, K.; Foggin, Chris M.; Muvavarirwa, P.; Honywill, J.; Pawandiwa, A.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1995)
Bastianello, Stella S.; Fourie, Niel; Nel, P.W.; Kellerman, T. Stephanus(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1995)