Kheoruenromne, Irb, Anchalee Suddhiprakarn, and Attasit Wongmaneeroj. 1997. “Properties and Landscape Relationship of Skeletal Soils in Upper Northeast, Thailand”. Agriculture and Natural Resources 31 (2). Bangkok, Thailand:237-53. https://li01.tci-thaijo.org/index.php/anres/article/view/240827.