TOBORG, Imke; VOLKMANN, Peter. On stability of the Cauchy functional equation in groupoids. Annales Mathematicae Silesianae, [S. l.], v. 31, p. 155–164, 2016. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/13947. Acesso em: 5 dec. 2025.