TABOR, Józef. On some characterization of the absolute value of an additive function. Annales Mathematicae Silesianae, [S. l.], v. 8, p. 69–77, 1994. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14218. Acesso em: 16 dec. 2025.