1. Soil Organic Matter and its Role in Crop Production;Allison,1973
2. Techniques for determining root length infected by vesicular-arbuscular mycorrhizae;Amber;Soil Science Society of America Journal,1977
3. Standard Methods for the Examination of Water and Wastewater,1975
4. Methods of Soil Analysis,1965
5. Effect of Sewage Sludge on the Cadmium and Zinc content of Crops;Council for Agricultural Science Technology (CAST),1980