MITROPOLSKIY, Yu. A.; KHOMA, N. H.; KHOMA, G. P. Conditions of solvability of quasilinear periodic boundary-value problems for hyperbolic equations of the second order. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 6, p. 818–821, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4892. Acesso em: 7 dec. 2025.