Waweru, J.G.; Kanyari, P.W.N.; Mwangi, D.M.; Ngatia, T.A.; Nansen, P.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999)
Van der Merwe, P.; Meltzer, David George Anton; Van Aswegen, G.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999)