OPSAL, Hilde; TOPPHOL, Arne Kåre. The problematic equal sign. NOMAD Nordic Studies in Mathematics Education, [S. l.], v. 28, n. 1-2, p. 99–112, 2023. DOI: 10.7146/nomad.v28i1-2.149263. Disponível em: https://tidsskrift.dk/NOMAD/article/view/149263. Acesso em: 6 dec. 2025.