แสงทามาตย์พ., สอนนาป., and อินทชัยพ. “The Comparison of Cost and Return Dried and Boiled Rock Salt in Ban Chai Sub-District, Ban Dung District, Udon Thani Province”. Journal of Roi Et Rajabhat University, Vol. 13, no. 1, Apr. 2019, pp. 151-6, https://www.tci-thaijo.org/index.php/reru/article/view/186030.