On the regularity of the solution to the hyperbolic equation. Kazakh Mathematical Journal, [S. l.], v. 22, n. 1, p. 28–43, 2024. DOI: 10.70474/qeyab577. Disponível em: https://mathjournal.kz/index.php/kmj/article/view/6. Acesso em: 31 jan. 2025.