BobykI. O. and PtashnikB. I. (1994) “Boundary-value problems for hyperbolic equations with constant coefficients”, Ukrains’kyi Matematychnyi Zhurnal, 46(7), pp. 795–802. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5669 (Accessed: 6October2024).