Rachma, Andina Aulia, and Rizky Rosjanuardi. “Students’ Obstacles in Learning Sequence and Series Using Onto-Semiotic Approach”. Mathematics Education Journal 15, no. 2 (June 30, 2021): 115–132. Accessed April 17, 2025. https://jpm.ejournal.unsri.ac.id/index.php/jpm/article/view/231.