1. M. Alexander, in: Biological Nitrogen Fixation in Farming Systems of the Tropics (A. Ayanaba and P. J. Dart, eds.), Wiley, Chichester, U.K., pp. 99–114 (1977).
2. M. Alexander, Annu. Rev. Microbiol., 35: 113–133 (1981).
3. B. B. Bohlool, and E. L. Schmidt, Soil Sci., 110: 229–236 (1970).
4. J. Brockwell, E. A. Schwinghamer, and R. R. Gault, Soil Biol. Biochem., 9: 19–24 (1977).
5. O. C. Bryan, Soil Sci., 15: 37–40 (1923).