RAJAGOPAL, C. T. On an absolute constant for a class of power series. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 267–270, 1957. DOI: 10.7146/math.scand.a-10504. Disponível em: https://www.mscand.dk/article/view/10504. Acesso em: 29 apr. 2024.