Difficulty level of arithmetic word problems in Singaporean and Spanish textbooks. Advances of Research in Mathematics Education, [S. l.], n. 22, p. 137–156, 2022. DOI: 10.35763/aiem22.4412. Disponível em: https://aiem.es/aiem/article/view/v22-vicente-verschaffel-ramos. Acesso em: 20 may. 2026.