Fakchareonphol, W., K. Nugultham, T. Wannagatesiri, and N. Kruea-in. “School performance indicator on improving student learning achievement through O-NET scores: Factor analysis on student prior achievement and size of the school”. Kasetsart Journal of Social Sciences, vol. 39, no. 2, Aug. 2018, pp. 780-8, https://so04.tci-thaijo.org/index.php/kjss/article/view/242546.