FRÖBERG, Ralph. Determination of a class of Poincaré series. Mathematica Scandinavica, Berkeley, CA, United States, v. 37, p. 29–39, 1975. DOI: 10.7146/math.scand.a-11585. Disponível em: https://journals.msp.org/mscand/article/view/2088. Acesso em: 25 jul. 2026.