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://journals.scholarpublishing.org/index.php/ASSRJ/article/view/3755. Acesso em: 31 mar. 2026.