ISRIANI, W. P.; SAFITRI, U. . Preliminary Observation of Problem-Based Learning to Improve Elementary Students’ Mathematical Problem-Solving Skills. TOFEDU: The Future of Education Journal, [S. l.], v. 4, n. 6, p. 1812–1819, 2025. DOI: 10.61445/tofedu.v4i6.665. Disponível em: http://journal.tofedu.or.id/index.php/journal/article/view/665. Acesso em: 13 jul. 2025.