Spencer, J.A.; Van Dijk, A.A.; Horzinek, Marian C.; Egberink, H.F.; Bengis, Roy G.; Keet, D.F.; Morikawa, S.; Bishop, D.H.L.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1992)
Kotze, Sanet H.; Van der Merwe, N.J.; Van Aswegen, G.; Smith, G.A.(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 1992)