A. Fahmi, B. Radjagukguk, and B. H. Purwanto, “Interaction of Peat Soil and Sulphidic Material Substratum: Role of Peat Layer and Groundwater Level Fluctuations on Phosphorus Concentration”, j Trop. Soils, vol. 19, no. 3, pp. 171–179, Oct. 2015.