1. Banwart, G. J., and Ayres, J. C. (1953). Appl. Microbiol., 1, 296.
2. Biechteler, W. (1952). Zbl. Bakt., Orig., 158, 53.
3. Dold, H., and Ketterer, M. (1943). Z. Hyg. InfektKr., 125, 215.
4. Gillert K. E. (1954). Zbl. Bakt., Orig., 160, 463.
5. Hobbs, B. C., and Allison, V. D. (1945). Monthly Bull. Minist.