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 September 28, 2026. https://he01.tci-thaijo.org/index.php/AIHD-MU/article/view/212481.