Usipbek , Z., D. Aubakir, D. Bexapar, Zh. Ashirkhan, and A. Shekerbek. “THE DARBOUX AND KOSHI PROBLEM FOR LINEAR HYPERBOLIC EQUATIONS WITH CONSTANT COEFFICIENTS ”. EurasianUnionScientists 6, no. 12(81) (January 18, 2021): 15-18. Accessed April 3, 2025. https://archive.euroasia-science.ru/index.php/Euroasia/article/view/375.