1. 1. BOROFF, D. A. and FLECK, U. (1966) : J. Bacteriol., 92, 1580-1581.
2. 2. SAKAGUCHI, G., SAKAGUCHI, S. and KONDO, H. (1968) : Japan. J. Med. Sci. Biol., 21, 369-378.
3. 3. FINNEY, D. J. (1964) : Statistical methods in biological assay. 2nd ed. Charles Griffin & Co., London. 668p.
4. 4. LAMANNA, C., SPERO, L.and SCHANTZ, E. J. (1970) : Infect. Immun., 1, 423-424.
5. 5. KOZAKI, S., SAKAGUCHI, S. and SAKAGUCHI, G. (1974) : Infect. Immun., 10, 750-756.