Khrueakham, Anurak, Bundit Anurugsa, and Natha Hungspreug. 2015. “Influence of Chemical Fertilizer Applications on Water Quality in Paddy Fields in Nong Harn, Sakon Nakhon Province, Thailand”. Agriculture and Natural Resources 49 (6). Bangkok, Thailand:868-79. https://li01.tci-thaijo.org/index.php/anres/article/view/243791.