1. Report of the sub-committee on the disposal of sewage sludge to land;Department of the Environment/National Water Council;Standing Technical Report No. 20,1981
2. ADAS Sampling soil for analysis,1979
3. Council Directive on the protection of the environment and in particular of the soil, when sewage sludge is used in agriculture;Council of the European Communities;Official Journal of the European Communities,1986
4. Use of sewage sludge in agriculture;Department of the Environment;National code of practice (draft),1987
5. Godwin R. J. Silsoe College. Personal communication, 1985