Rungsit Suwanketnikom, and Supranee Impitaksa. “Herbicide Concentration in Runoff and sediment from Experimental plots of Highland Cultivated Areas”. Agriculture and Natural Resources, vol. 25, no. 3, Sept. 1991, pp. 358-69, https://li01.tci-thaijo.org/index.php/anres/article/view/241985.