Ngwe, Kyaw, Irb Kheoruenromne, and Anchalee Suddhiprakarn. 2012. “Potassium Status and Physicochemical and Mineralogical Properties of Lowland Vertisols in a Rice-Based Cropping System under Tropical Savanna Climate”. Agriculture and Natural Resources 46 (4). Bangkok, Thailand:522-37. https://li01.tci-thaijo.org/index.php/anres/article/view/242906.