KIRILICH, V. M.; FIRMAN, T. I. Problem without initial conditions for a countable semilinear hyperbolic system of first-order equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 8, p. 1043–1055, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1900. Acesso em: 5 dec. 2025.