1. Bridger, J. C. (1988).Journal of Medical Microbiology,27, xi-xii.
2. Henriksen, S. A. &Pohlenz, J. F. L. (1981).Acta Veterinaria Scandinavica,22, 594–596.
3. Langpap, T. J., Bergeland, M. E. &Reed, D. E. (1979).American Journal of Veterinary Research,40, 1476–1478.
4. Marsolias, G., Assaf, R., Montpetit, C. &Marois, P. (1978).Canadian Journal of Comparative Medicine,42, 168–171.
5. Moon, H. W., McClurkin, A. W., Isaacson, R. E., Pohlenz, J., Skartvedt, S. M., Gilette, K. G. &Baetz, A. L. (1978).Journal of the American Veterinary Medical Association,173, 577–583.