Muhammad, H. et al. 2005. The Rate of S-Element Transformation to Sulfate on Three Kinds of Soils With and Without Addition of Organic Matter. Jurnal Ilmu Tanah dan Lingkungan. 7, 1 (Apr. 2005), 15–21. DOI:https://doi.org/10.29244/jitl.7.1.15-21.