Khowjoy, Kritchai. “Relationship between Key Factors of Operation Management Affecting the Operation Cost in Phetchabun Small and Medium Industrial Entrepreneurs: Variables in Manufacture Defect and Operating Times”. Ratchaphruek Journal 20, no. 1 (March 25, 2022): 14–26. accessed September 11, 2026. https://so05.tci-thaijo.org/index.php/Ratchaphruekjournal/article/view/253654.