FILASETA, Michael; SOLAN, Ikhalfani. 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://tidsskrift.dk/math/article/view/13928. Acesso em: 13 aug. 2026.