1. Determination of total, organic and available forms of phosphorus in soils;Bray;Soil Sci.,1945
2. A comparative study of phosphorus uptake by plant and available phosphorus content in the soils of Egypt as determined by chelating compound extracts;Hanna;J. Soil Sci., U.A.R.,1962
3. Soil Chemical Analysis;Jackson,1958
4. Phosphate fixation and exchange of phosphate and hydroxyl ions;Kelly;Soil Sci.,1943
5. Chemical diagnosis by the Universal Soil Testing System;Morgan,1941