ALDASHEV, S. A. Well-posedness of mixed problems for multidimensional hyperbolic equations with wave operator. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 69, n. 7, p. 992–999, 2017. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1752. Acesso em: 5 dec. 2025.