FILASETA, M.; SOLAN, I. An extension of a theorem by Ljunggren. MATHEMATICA SCANDINAVICA, [S. l.], v. 84, n. 1, p. 5–10, 1999. DOI: 10.7146/math.scand.a-13928. Disponível em: https://www.mscand.dk/article/view/13928. Acesso em: 2 may. 2024.