Lekskulchai, Veeravan. “Urinary nicotine and cotinine concentrations in hand-rolled cigarette smokers, filter cigarette smokers, and passive smokers exposed to ETS”. Thai Journal of Toxicology 25, no. 2 (June 4, 2020): 60. accessed April 26, 2025. https://li01.tci-thaijo.org/index.php/ThaiJToxicol/article/view/243923.