Van Aswegen, G.; De Vos, Valerius; Schoeman, J.H.; Van Noorden, Susan; Kotze, Sanet H.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)
Grant, C.C. (Catharina Cornelia); Biggs, H.C.; Meissner, H.H.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)