1. Differences in availability to crops of cadmium in sewage-sludge amended soils compared with other organic sources;Alloway,1984
2. Trace elements in soils in England and Wales;Archer,1980
3. Sources and distribution of trace elements in soils and related crops;Berrow,1979
4. Trace element levels in soils: effects of sewage sludge;Berrow,1980
5. Background levels of trace elements in soils;Berrow,1984