SARAGIH, Sahat; ., Syafari; ., Muliyono. The Validity of Problem Based Learning Model To Improve Problem Solving Ability. Advances in Social Sciences Research Journal, [S. l.], v. 5, n. 2, 2018. DOI: 10.14738/assrj.52.3755. Disponível em: https://scholarpublishing.org/journals/index.php/ASSRJ/article/view/11722. Acesso em: 28 may. 2026.