Estrada-Pena, Agustín(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003)
Stenson, M.O.; Van der Merwe, J.S.; Vorster, R.J.; Viljoen, P.G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999)