Tapdigoglu, R., and B.T. Torebek. “Inverse Source Problems for a Wave Equation With Involution”. Bulletin of the Karaganda University. Mathematics Series 91, no. 3 (September 29, 2018): 75–82. Accessed July 10, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/284.