ใต้ไธสง ภ. “HAPPINESS AT WORK OF EMPLOYEE AT TRUE DISTRIBUTION AND SALES COMPANY LIMITED, REGIONAL UPPER NORTHEAST”. Valaya Alongkorn Review, vol. 8, no. 1, Apr. 2018, pp. 15-35, https://so06.tci-thaijo.org/index.php/var/article/view/146930.