Yusubov, Sh. Sh. “Nonlocal Problem With Integral Conditions for a High-Order Hyperbolic Equation”. Ukrains’kyi Matematychnyi Zhurnal 69, no. 1 (January 25, 2017): 121-131. Accessed September 26, 2022. http://umj.imath.kiev.ua/index.php/umj/article/view/1681.