AMEUR, Y. A note on a theorem of Sparr. MATHEMATICA SCANDINAVICA, [S. l.], v. 94, n. 1, p. 155–160, 2004. DOI: 10.7146/math.scand.a-14435. Disponível em: https://www.mscand.dk/article/view/14435. Acesso em: 27 apr. 2024.