Kamlap, Duangjai. “Application of Sigma Metrics for Evaluation and Improvement of Quality Control in the Clinical Chemistry Laboratory of Udon Thani Cancer Hospital”. Journal of The Department of Medical Services 51, no. 3 (September 15, 2026): 66–74. accessed September 18, 2026. https://he02.tci-thaijo.org/index.php/JDMS/article/view/276673.