Salam, A. K., and K. Ginanjar. “Tropical Soil Labile Fractions of Copper in the Experimental Plots ±Ten Years After Application of Copper-Containing-Waste”. JOURNAL OF TROPICAL SOILS, vol. 23, no. 1, Mar. 2018, pp. 11-18, doi:10.5400/jts.2018.v23i1.11-18.