Nanthapornsak, S., and L. Manmart. “The Factors Affecting Physicians’ Employee Engagement of Private Hospitals in the Northeastern Region, Thailand”. KKU Research Journal (Graduate Studies) Humanities and Social Sciences, vol. 7, no. 2, July 2019, pp. 145-62, https://so04.tci-thaijo.org/index.php/gskkuhs/article/view/206779.