Mitropolskiy, Y.A., Khoma, N.H. and Khoma, G.P. (1998) “Conditions of solvability of quasilinear periodic boundary-value problems for hyperbolic equations of the second order”, Ukrains’kyi Matematychnyi Zhurnal, 50(6), pp. 818–821. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4892 (Accessed: 10 April 2025).