SAMUSENKO, P. F. Asymptotic integration of singularly perturbed systems of hyperbolic-type partial differential equations with degeneration. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 5, p. 668–685, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2752. Acesso em: 5 dec. 2025.