1. Abrahamsen, G., Horntvedt, R., and Tveite, B.: 1976, Impacts of Acid Precipitation on Coniferous Forest Ecosystems’, in Dochinger, L. S. and Selinga, T. A. (eds.), Symp. on Acid Precipitation and the Forest Ecosystem, USDA Forest Service General Tech. Rep. NE-23, p. 991.
2. Abrahamsen, G., Hovland, J., and Hagvar, S.: 1980, ‘Effects of Artificial Acid Rain and Liming on Soil Organisms and the Decomposition of Organic Matter’, in Hutchinson, T. C. and Havas, M. (eds.), Effects of Acid Precipitation on Terrestrial Ecosystems, Plenum, New York, p. 341.
3. Alexander, M.: 1980a, ‘Effects of Acidity on Microorganisms and Microbial Processes in Soil’, in Hutchinson, T. C. and Havas, M. (eds.), Effects of Acid Precipitation on Terrestrial Ecosystems, Plenum, New York, p. 363.
4. Alexander, M.: 1980b, ‘Effects of Acid Precipitation on Biochemical Activities in Soil’, in Drables, D. and Tollan, A. (eds.), Proc. Int. Conf. Ecol. Impact Acid Precip., SNSF Project, Norway, p. 47.
5. Alexander, M. and Clark, F. E.: 1965, `Nitrifying Bacteria’, in Black, C. A. (ed.),Methods of Soil Analysis, Part 2, Amer. Soc. of Agronomy, Madison, WI.