BOLTAEVA , M. THE EXISTENCE OF A SOLUTION OF A NONLOCAL PROBLEM FOR THE WAVE EQUATION OF A STRING. International Bulletin of Engineering and Technology, [S. l.], v. 4, n. 8, p. 9–12, 2024. Disponível em: https://internationalbulletins.com/intjour/index.php/ibet/article/view/1620. Acesso em: 6 apr. 2026.