NORBERG, M. Exercise design in mathematics textbooks: the case of subtraction. NOMAD Nordic Studies in Mathematics Education, [S. l.], v. 26, n. 1, p. 5–29, 2021. DOI: 10.7146/nomad.v26i1.149147. Disponível em: https://tidsskrift.dk/NOMAD/article/view/149147. Acesso em: 8 jan. 2025.