Lertkovit, Saranya, Aree Sangsai, Orawan Supapueng, and Phongthara Vichitvejpaisal. 2023. “Six Sigma: in Pursuit of Zero Tolerance in Anesthesia”. Thai Journal of Anesthesiology 49 (1):55-62. https://he02.tci-thaijo.org/index.php/anesthai/article/view/260786.