1. Baruah M. and R.R. Mishra, 1984. Dehydrogenase and urease activities in rice-field soils. Soil Biol. Biochem., 16, 423–424.
2. Boyd S.A. and M.M. Mortland, 1990. Enzyme interactions with clays and clay-organic matter complex. In: J. M. Bollag and G. Stotzky (Editors), Soil Biochemistry, Vol.6. Marcel Dekker, New York, pp. 1–28.
3. Burns R.G., A.H. Pukite and A.D. McLaren, 1972. Concerning the location and persistence of soil urease. Soil Sci. Soc. Am. Proc., 36, 308–311.
4. Bums R.G., 1986. Interaction of enzymes with soil mineral and organic colloids. In: P.M. Huang and M. Schnitzer (Editors), Interaction of Soil Minerals with Natural Organics and Microbes. Soil Sci. Soc. Amer., Madison, pp.429–451.
5. Carter D.L., M.D. Heilman and C.L. Gonzalez, 1965. Ethylene glycol monoethyl ether for determining surface area of silicate minerals. Soil Sci., 100, 356–360.