PARTANEN, A.-M.; TOLVANEN, P. Developing a frame for analysing different meanings of the concept of variable mediated by tasks in elementary-school mathematics textbooks. NOMAD Nordic Studies in Mathematics Education, [S. l.], v. 24, n. 3-4, p. 59–79, 2019. DOI: 10.7146/nomad.v24i3-4.149024. Disponível em: https://tidsskrift.dk/NOMAD/article/view/149024. Acesso em: 7 jan. 2025.