“Effectiveness of Android-Based Learning Media “Teman Ritma” to Improve Problem-Solving Skills of SMP Negeri 5 Yogyakarta”. Jurnal Mercumatika : Jurnal Penelitian Matematika dan Pendidikan Matematika 6, no. 2 (April 30, 2022). Accessed June 30, 2026. https://ejurnal.mercubuana-yogya.ac.id/index.php/mercumatika/article/view/2447.