Rachma AA, Rosjanuardi R. Students’ Obstacles in Learning Sequence and Series Using Onto-Semiotic Approach. Math. Educ. J. [Internet]. 2021 Jun. 30 [cited 2025 Apr. 17];15(2):115-32. Available from: https://jpm.ejournal.unsri.ac.id/index.php/jpm/article/view/231