Wonginta, A., & Pavaputanon, L. (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. retrieved from https://so02.tci-thaijo.org/index.php/EDGKKUJ/article/view/241791