1. Alexander, M. (1978). Introduction to Soil Microbiology. Wiley, New York and London.
2. Bajpai, R.D. (2003). Non-legumes too can fix their own nitrogen. Personal Communication, Department of Agronomy, J.N. Krishi, Vishwa Vidyalaya, Jabalpur, Madhya Pradesh, India.
3. Biswas, B.C., Das, S. and Kalwae, S.P. (2001). Crop response to bio-fertilizers. Fertilizers News 46 (2): 15–18.
4. De, P.K. and Sarkar, S.N. (1936). Transformation of nitrate in waterlogged soils. Soil Sci. 42 (1): 143–155.
5. De, P.K. and Bose, N.M. (1938). A study of the microbiological conditions existing in rice soils. Indian J. Agric. Sci. 8 (4): 487–498.