1. The determination of nitrogen in heavy clay soils;Bal;J. Agric. Sci.,1925
2. National Bureau of Soil Survey and Land Use Planning;Benchmark Soils of India,1982
3. Comparison and evaluation of methods of determining fixed ammonium in soils;Bremner,1967
4. Nitrogen availability in SAT soils: Environment effects on soil processes;Burford,1989
5. Cation exchange capacity;Chapman,1965