ARITONANG, A. R.; MINARNI, A.; RAJAGUKGUK, W. Analysis of Differences in Improvement of Mathematical Problem Solving Ability of The Students at Upper Secondary School 3 Sidikalang Based on Contextual Learning Model And Direct Learning Models. Advances in Social Sciences Research Journal, [S. l.], v. 5, n. 9, 2018. DOI: 10.14738/assrj.59.5226. Disponível em: https://journals.scholarpublishing.org/index.php/ASSRJ/article/view/5226. Acesso em: 27 apr. 2024.