1. Allison, F.E. 1955. The enigma of soil nitrogen balance sheets, pp. 213–250. In: Norman, A.G. (ed.) Advances in Agronomy, vol. 3. Academic Press, N.Y.
2. Arah, J.R.M., and K.A. Smith. 1989. Steady-state denitrification in aggregated soils: a mathematical model. J. Soil Sci. 40: 139–149.
3. Arah, J.R.M., and K.A. Smith. 1990. Factors influencing the fraction of the gaseous products of soil denitrification evolved to the atmosphere as nitrous oxide, pp. 475–480. In: Bouwman, A.F. (ed.) Soils and the Greenhouse Effect. Wiley, Chichester.
4. Armstrong, W. 1979. Aeration in higher plants. Adv. Bot. Res. 7: 225–332.
5. Aulakh, M.S. 1986a. Gaseous losses of nitrogen from soils through biological processes: a review, pp. 99–115. In: Mishra, M.M., Kappor, K.K. (eds.) Soil Biology. Haryana Agric. Univ. Hissar, India.