(2) D. K. Dougall: Plant Physiol., 40, 891 (1965).
(3) D. K. Dougall: Plant Physiol., 41, 1411 (1966).
(4) D. K. Dougall and M. M. Fulton: Plant Physiol., 42, 941 (1967).
(5) E. Unberger and B. D. Davis: “The Bacteria,” Vol. III, ed. by I. C. Gunsalus and R. Y. Stanier, Academic Press., New York, N. Y., 1962, pp. 167-251.