Pamonpol, Kanittha, and Natsima Tokhun. “Heavy Metal Contamination at Highland Agricultural Soil at Dan Sai District, Loei Province, Thailand”. Journal of Public Health and Development 17, no. 3 (December 27, 2019): 13–22. Accessed May 21, 2024. https://he01.tci-thaijo.org/index.php/AIHD-MU/article/view/212481.