Siripak, Sunida. “The Development of Non-Formal Education Activities Model Based on McClelland’s Achievement Motivation Theory to Enhance Achievement Motivation, Self-Concept, and Increasing English Achievement Scores of Non-Formal Education Leaders”. Scholar: Human Sciences 3, no. 1 (October 16, 2014). Accessed April 28, 2024. http://www.assumptionjournal.au.edu/index.php/Scholar/article/view/256.