KOSI-ULBL, Irena. On a functional equation related to two-sided centralizers. Annales Mathematicae Silesianae, [S. l.], v. 32, p. 227–235, 2018. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/13922. Acesso em: 5 dec. 2025.