WINTNER, A. The theorem of Eneström and the extremal functions of Landau-Schur. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 236–240, 1957. DOI: 10.7146/math.scand.a-10500. Disponível em: https://www.mscand.dk/article/view/10500. Acesso em: 29 apr. 2024.