ZHESTKOV , S. V.; ERMOLAEV , E. A. One algebraic method to study stability of linear normal systems in partial derivatives. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 4, p. 480–489, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7889. Acesso em: 6 dec. 2025.