Pikunsri, T., C. Chueasathuchon, and C. Chueasathuchon. “Variables Affecting Ability in Mathematical Reasoning of Matthayom Suksa 1 Students at Opportunity Expansion Schools under the Amnatcharoen Primary Educational Service Area Office”. Ubon Ratchathani Journal of Research and Evaluation, vol. 6, no. 2, Aug. 2021, pp. 81-90, https://so06.tci-thaijo.org/index.php/ubonreseva/article/view/251049.