Ulfah, Alfiatun Fitriani, and Rully Charitas Indra Prahmana. 2018. “Single Subject Research: Implementasi Pembelajaran Berbasis Masalah Terhadap Pemahaman Matematis Siswa”. Jurnal Elemen 4 (1):105-18. https://doi.org/10.29408/jel.v4i1.553.