Kutlay, H., and A. Yakar. “Existence of Extremal Solutions for a Class of Fractional Integro-Differential Equations”. Bulletin of the Karaganda University. Mathematics Series 115, no. 3 (September 30, 2024): 112–125. Accessed July 1, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/819.