Wonginta, Arisa, and Lha Pavaputanon. 2018. “The Study of Grade 8 Students’ Algebraic Thinking in Solving Problems of Factoring One Variable Polnomials of Degree 2”. Journal of Innovation and Learning Sciences 12 (3):1-9. https://so02.tci-thaijo.org/index.php/EDGKKUJ/article/view/241791.