ALDASHEV, S. A. Existence of eigenfunctions of the Tricomi spectral problem for some classes of multidimensional mixed hyperbolic–parabolic equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 6, p. 723 – 732, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2904. Acesso em: 5 dec. 2025.