1. Allen, O. N., Experiments in Soil Bacteriology. Burgess Publishing Co., Minneapolis (1957).
2. Aseeva, I. V. and Kirillova, N. F., Action of soil dwelling bacteria on free amino acid content of leguminosae. Nauch. Dokl. Vyssh. Shkoly. Biol. Nauki. No. 1, 139 (Russian) Chem. Abstr.55 (3896), (1960).
3. Biswas, T. D. and Das, N. B., Amino acids in soils growing berseem. J. Indian Soc. Soil Sci.5, 31 (1957).
4. Giri, K. V. and Rao, N. A. N., A technique for the identification of amino acids separated by circular paper chromatography. Nature169, 923 (1952).
5. Hewitt, E. J., Sand and water culture methods used in the study of plant nutrition. Commonwealth Bur. Hort Plantation. Crops Tech. Commun.22, East Malling (1952).