Aitzhanov, S. E., Bekenaeva К. S., and Zhumagul G. О. “Solvability of a Pseudohyperbolic Equation With a Nonlinear Boundary Condition”. Journal of Mathematics, Mechanics and Computer Science 108, no. 4 (December 30, 2020): 26–37. Accessed December 4, 2024. https://bm.kaznu.kz/index.php/kaznu/article/view/817.