YUSUBOV, Sh. Sh. Goursat-Type Problem for a Higher-Order Equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 6, p. 874–880, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2474. Acesso em: 27 apr. 2025.