HJELLE, T.; KLOVE, T. Congruence Properties and Density Problems for the Fourier Coefficients of Modular Forms. MATHEMATICA SCANDINAVICA, [S. l.], v. 23, p. 160–166, 1968. DOI: 10.7146/math.scand.a-10905. Disponível em: https://www.mscand.dk/article/view/10905. Acesso em: 8 may. 2024.