DOMAR, Y. A Theorem of Beurling-Helson Type. MATHEMATICA SCANDINAVICA, [S. l.], v. 33, p. 139–144, 1973. DOI: 10.7146/math.scand.a-11479. Disponível em: https://www.mscand.dk/article/view/11479. Acesso em: 23 jul. 2024.