“Improvement of Soil Chemistry Characteristic of Upland with Rock Phosphate, Phosphate-Solubilizing Bacteria and Farm Yard Manure For Increase of Soybean Yield”, j Trop. Soils, vol. 13, no. 1, pp. 49–58, Jan. 2008, doi: 10.5400/jts.2008.v13i1.49-58.