TOPARKUS, H. First-order systems of linear partial differential equations: normal forms, canonical systems, transform methods. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica, [S. l.], v. 13, p. 109–132, 2014. Disponível em: https://studmath.uken.krakow.pl/article/view/13194. Acesso em: 29 oct. 2026.