Tarasov, V.G. and Nizhnik, L.P. (1999) “Direct and inverse scattering problems for multidimensional system of first-order partial differential equations”, Methods of Functional Analysis and Topology, 5(2), pp. 44–82. Available at: https://zen.imath.kiev.ua/index.php/mfat/article/view/89 (Accessed: 17 December 2025).