FIDYTEK, Irena. Stability of a system of generalized trigonometric equations. Annales Mathematicae Silesianae, [S. l.], v. 9, p. 81–100, 1995. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14209. Acesso em: 26 apr. 2025.