ANDRUSYAK, R.V.; KYRYLYCH, V.M.; Peliushkevych О.V. A problem for degenerated semilinear hyperbolic system in sector. Carpathian Mathematical Publications, [S. l.], v. 3, n. 2, p. 4–12, 2011. Disponível em: https://scijournals.pnu.edu.ua/index.php/cmp/article/view/3060. Acesso em: 3 may. 2024.