SZOSTOK, Tomasz. On some conditional functional equations. Annales Mathematicae Silesianae, [S. l.], v. 16, p. 65–77, 2003. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14109. Acesso em: 7 may. 2025.