Dedi Irawan, Bornok Sinaga, and Elmanani Simamora. “Developing a Learning Tool Based on the Problem-Based Learning Model to Improve Students’ Problem Solving and Collaboration Skills”. Jurnal Perspektif 10, no. 1 (May 11, 2026): 237–247. Accessed May 14, 2026. http://perspektif.uinsgd.ac.id/index.php/JP/article/view/458.