GER, Joanna. On analytic solutions of the non-linear functional equation. Annales Mathematicae Silesianae, [S. l.], v. 1, p. 103–115, 1985. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14340. Acesso em: 5 dec. 2025.