Assanova, A. T. and Dzhumabaev, D. S. (2004) “Periodic solutions of systems of hyperbolic equations bounded on a plane”, Ukrains’kyi Matematychnyi Zhurnal, 56(4), pp. 562-572. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3777 (Accessed: 28April2024).