Noor, A. “Improvement of Soil Chemistry Characteristic of Upland With Rock Phosphate, Phosphate-Solubilizing Bacteria and Farm Yard Manure For Increase of Soybean Yield”. JOURNAL OF TROPICAL SOILS, vol. 13, no. 1, Jan. 2008, pp. 49-58, doi:10.5400/jts.2008.v13i1.49-58.