NizhnikL. P., and TarasovV. G. “Scattering Problem for a Multidimensional System of First-Order Partial Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 51, no. 8 (August 25, 1999): 1065–1076. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4697.