“Symmetrization of systems of conservation equations and the converse to the condition of Friedrichs and Lax”, Arch. Mech., vol. 49, no. 5, pp. 865–876, Jan. 1997, Accessed: Sep. 19, 2025. [Online]. Available: https://am.ippt.pan.pl/index.php/am/article/view/v49p865