Porprasit, Nujaree, Ann Jirapongsuwan, Surintorn Kalampakorn, and Sukhontha Siri. 2020. “Factors associated with quality of spirometry at occupational medicine clinic in Nopparat Rajathanee Hospital”. Journal of Medicine and Health Sciences 27 (3):69-82. https://he01.tci-thaijo.org/index.php/jmhs/article/view/246817.