BYSZEWSKI, Ludwik. Existence and uniqueness of classical solution to Darboux problem together with nonlocal conditions. Annales Mathematicae Silesianae, [S. l.], v. 27, p. 67–74, 2013. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14002. Acesso em: 5 dec. 2025.