กีรติวิบูลย์ วรางคณา. “Factors Influencing on Learning Achievement of Calculus 1 for Thaksin University’s Students”. Parichart Journal 28, no. 1 (November 30, 2015): 98–117. accessed September 11, 2026. https://so05.tci-thaijo.org/index.php/parichartjournal/article/view/43171.