Pimolsiri Supasatienchai, Jongruk Chanchareonsook, and Ed Sarobol. “Utilization of Slop Ash as a Source of Potassium for Corn Grown on the Pakchong Soil Series”. Agriculture and Natural Resources, vol. 44, no. 1, Feb. 2010, pp. 17-23, https://li01.tci-thaijo.org/index.php/anres/article/view/244876.