On a boundary-value problem with data on non-characteristic intersecting lines for a system of hyperbolic equations with mixed derivative. Neliniini Kolyvannya, [S. l.], v. 15, n. 1, p. 3–12, 2012. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/630. Acesso em: 21 jan. 2026.