Lertvichai, R. “Guidelines for Self-directed Learning Ability Development of Social Development and Human Security Volunteers in Nakhon Ratchasima Provinc”. Ratchaphruek Journal, vol. 19, no. 2, Aug. 2021, pp. 102-10, https://so05.tci-thaijo.org/index.php/Ratchaphruekjournal/article/view/249780.