Jintanasoontonsiri, S. “Development of a Non-Formal Education Program to Enhance the Cooperation in Mathematical Learning Based on Cooperative Learning Concept and Constructivist Theory for Non-Formal Education Students in Bangkok Metropolitan Area”. Scholar: Human Sciences, vol. 4, no. 2, Oct. 2014, https://assumptionjournal.au.edu/index.php/Scholar/article/view/166.