1. U.S. Congress, Office of Technology Assessment ‘Impacts of Technology on U.S. Cropland and Rangeland Productivity’,1982
2. U.S. Department of Agriculture, Study Team on Organic Farming ‘Report and Recommendations on Organic Farming’,1980
3. Organic Farming: Current Technology and Its Role in a Sustainable Agriculture;Vogtmann,1984
4. Fertilizer Application;Voisin,1965
5. Environmentally Sound Agriculture;Hodges,1983