Odendaal, M.W.; Pieterson, P.M.; De Vos, Valerius; Botha, A.D.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1991)
Gallivan, Gordon J.; De Vos, Valerius(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003)