Kriek, N.P.J.; Keet, D.F.; Raath, J.P.; De Vos, Valerius; Huchzermeyer, Hildegard F.A.K.; Bengis, Roy G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)
Grant, C.C. (Catharina Cornelia); Biggs, H.C.; Meissner, H.H.; Basson, P.A.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996)