ชมภู บ. (2010). Comparisons of Learning Achievements, Analytical Thinking Abilities, Satisfaction with Learning and Teaching, and Learning Retention in the Mathematics Learning Strand Entitled Trigonometrical Ratios of Matthayomsueksa 4 Students Using Courseware Geometer’s Sketchpad Approach (CGS) and the Conventional Teaching Approach. Academic Journal of Thailand National Sports University, 2(1), 155–165. retrieved from https://he02.tci-thaijo.org/index.php/TNSUJournal/article/view/252168