Nabilah, Azzah, and Candra Utama. “Effectiveness of Problem-Based Learning (PBL) in Improving Students’ Mathematical Ability: Results of a Literature Review”. Khalifah : Jurnal Pendidikan Nusantara, vol. 2, no. 2, May 2025, pp. 107-15, https://doi.org/10.62523/khalifah.v2i2.13.