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)
Van der Merwe, P.; Meltzer, David George Anton; Van Aswegen, G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999)