FRÖBERG, R. Determination of a class of Poincaré series. MATHEMATICA SCANDINAVICA, [S. l.], v. 37, p. 29–39, 1975. DOI: 10.7146/math.scand.a-11585. Disponível em: https://www.mscand.dk/article/view/11585. Acesso em: 7 apr. 2025.