Sagala, Prihatin Ningsih. “APPLICATION OF PROBLEM-BASED LEARNING MODELS TO IMPROVE STUDENTS’ MATHEMATICAL CREATIVE THINKING ABILITIES”. REKOGNISI : Jurnal Pendidikan Dan Kependidikan (E-ISSN 2599-2260), vol. 3, no. 1, June 2018, pp. 61-80, https://jurnal.unusu.ac.id/index.php/rekognisi/article/view/79.