Roonapai, R. and Disyabutra, L. (1992) “The Role of 4-H Volunteer Leader in the Eastern Region”, Kasetsart Journal of Social Sciences, 13(2), pp. 149–156. available at: https://so04.tci-thaijo.org/index.php/kjss/article/view/244066 (accessed: 15 September 2026).