Khanitcharongkul, A. ., C. . Mangkhang, and C. . Wannapaisan. “PROBLEM–BASED LEARNING MANAGEMENT TO ENHANCE CITIZENSHIP SKILLS OF STUDENTS IN DEMONSTRATION SCHOOL UNIVERSITY OF PHAYAO”. Journal of Education and Innovation, vol. 22, no. 1, Dec. 2019, pp. 315-27, https://so06.tci-thaijo.org/index.php/edujournal_nu/article/view/94117.