Moldagali, Ye.O., and K.N. Ospanov. “Conditions for Maximal Regularity of Solutions to Fourth-Order Differential Equations”. Bulletin of the Karaganda University. Mathematics Series 116, no. 4 (December 30, 2024): 149–158. Accessed July 11, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/630.