An analysis of derivability theorems’ justifications in textbooks from the 70’s Spanish Education Law. Advances of Research in Mathematics Education, [S. l.], n. 8, p. 51–71, 2015. DOI: 10.35763/aiem.v1i8.117. Disponível em: https://aiem.es/aiem/article/view/3967. Acesso em: 20 may. 2026.