KILHAMN, C. When does a variable vary? Identifying mathematical content knowledge for teaching variables. NOMAD Nordic Studies in Mathematics Education, [S. l.], v. 19, n. 3-4, p. 83–100, 2014. DOI: 10.7146/nomad.v19i3-4.148649. Disponível em: https://tidsskrift.dk/NOMAD/article/view/148649. Acesso em: 8 jan. 2025.