จิรเศรษฐสิริ อ., and อัมมวรรธน์ ไ. “Factors Relating to the Happiness Level in Pakkret Hospital Personnel”. Journal of Preventive Medicine Association of Thailand, vol. 4, no. 2, Feb. 2019, pp. 118-24, https://he01.tci-thaijo.org/index.php/JPMAT/article/view/173027.