Siahaan, Yuni Hariati, et al. “Implementation of Problem-Based Learning Model to Improve Mathematical Problem-Solving Skills of Grade XI-2 Students of SMAN 19 Pekanbaru”. Jurnal Didactical Mathematics , vol. 8, no. 1, Apr. 2026, pp. 204-22, doi:10.31949/dm.v8i1.17437.