สุชิน ก., จันท์พิพัฒน์พงศ์ ธ. and เมืองใจ ท. (2020) “A STUDY AND DEVELOPMENT OF ENHANCING A MODEL FOR HAPPINESS BY USING THE FACTORS AFFECTING THE HAPPINESS OF THE ELDERLY OF CHIANG KHONG DISTRICT, CHIANG RAI PROVINCE ”, Research Community and Social Development Journal. Nakhon Ratchasima, Thailand, 14(3), pp. 58–71. doi: 10.14456/nrru-rdi.2020.45.