Boonwirat, Apichayada, and Parinyapast Seethong. 2022. “The Development of an Enrichment Curriculum on Mathematics Problem Solving Skills Using DAPIC Problem Solving Process for Sixth”. Journal of Humanities and Social Sciences, Rajapruk University 8 (2):465-80. https://so03.tci-thaijo.org/index.php/rpu/article/view/263001.