Suk-ueng, K., Chantima, K., and Prasertsin, T. “Spatial distribution of soil quality using geoinformatics in agricultural areas in Nang Lae Sub-district, Mueang District, Chiang Rai Province”. International Journal of Agricultural Technology, vol. 15, no. 5, Sept. 2019, pp. 779-90, https://li04.tci-thaijo.org/index.php/IJAT/article/view/8302.