DIRDAL, G. Congruence properties for a class of arithmetical functions. MATHEMATICA SCANDINAVICA, [S. l.], v. 38, p. 247–261, 1976. DOI: 10.7146/math.scand.a-11632. Disponível em: https://www.mscand.dk/article/view/11632. Acesso em: 24 nov. 2024.