เถาว์โท อมรรัตน์, and สราวุธ จิรัญญา. “The Development of Learning Achievement in Topic of Solving Polynomial Fractional of Ninth Grade Students by Using Problem-Based Learning Approach”. Journal of Graduate School, Pitchayatat, Ubon Ratchathani Rajabhat University 13, no. 2 (December 28, 2018): 245–254. Accessed May 19, 2024. https://so02.tci-thaijo.org/index.php/Pitchayatat/article/view/221666.