1. Bache, B.W., in The Encyclopaedia of Soil Science, eds. Fairbridge, R.W. and Finkl, C.W. Dowden, Hutchinson & Ross, Stroudsburg, Pa (1979), 487–492.
2. Wild, A. (ed.), Russell’s Soil Conditions and Plant Growth 11th edn. Longman, London (1988).
3. Brady, N.C., The Nature and Properties of Soils, 9th edn. Collier Macmillan, New York (1984).
4. Chen, Y. and Stevenson, F.J., in The Role of Organic Matter in Modern Agriculture, eds. Chen, Y. and Avinmelech, Y. Martinus Nijhoff, Dordrecht (1986), 73–112.
5. Stevenson, F.J., in Encyclopaedia of Soil Sciences, eds. Fairbridge, R.W. and Finkl, C.W. Dowden, Hutchinson & Ross, Stroudsburg, Pa (1979), 195–205.