1. BETTANY, J.R.; STEWART J.W.B.; HALSTEAD E.H.: Sulfur fractions and carbon, nitrogen and sulfur relationships in grassland, forest and associated transitional soils. Soil Sci. Soc. Am. Proc. 37, 915 - 918 (1973).
2. DODGSON, K.S.; WHITE, G.F.; FITZGERALD, J.W.: Sulfatases of microbial origin, VI. 1. CRC Press Inc, Boca Raton, Fla (1982).
3. FRENEY, J.R.: Forms and reactions of organic sulfur compounds in soils. In Tabatabai M.A. (ed.) Sulfur in agriculture. Soil Sci. Soc. Am., Madison, Wis, 707 - 232 (1986).
4. HEADLEY, M.J.; NYE, P.H.; WHITE, R.E.: Plant-induced changes in the rhizosphere of rape (Brassica napus var. Emerald) seedlings. II. Origin of the pH change. New Phytol. 91, 31 - 44 (1982).
5. LOWE, L.E.; DE LONG, W.A.: Carbon bonded sulphur in selected Quebec soils. Can. J. Soil Sci. 43, 151 - 155 (1963).