Chotigakham, T. “The Effectiveness of Program Happiness in Elderly: A Case Study of Elderly in Dongtakop Sub-District, Taphanhin District, Phichit Province”. Journal of Disease and Health Risk DPC.3, vol. 16, no. 1, Apr. 2022, pp. 18-34, https://he01.tci-thaijo.org/index.php/JDPC3/article/view/252220.