PRZYBYŁA, Maciej. The d’Alembert and Lobaczevski difference operators in ????_λ spaces. Annales Mathematicae Silesianae, [S. l.], v. 20, p. 7–17, 2006. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14065. Acesso em: 18 apr. 2025.