IL’INSKAYA, I. P. Arithmetic of semigroups of series in multiplicative systems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 7, p. 939–947, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3068. Acesso em: 5 dec. 2025.