MATKOWSKI, Janusz. On a system of simultaneous iterative functional equations. Annales Mathematicae Silesianae, [S. l.], v. 9, p. 123–135, 1995. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14212. Acesso em: 18 apr. 2025.