Efendiev, B.I. “An Analogue of the Lyapunov Inequality for an Ordinary Second-Order Differential Equation With a Fractional Derivative and a Variable Coefficient”. Bulletin of the Karaganda University. Mathematics Series 106, no. 2 (June 30, 2022): 83–92. Accessed December 8, 2025. https://mts.buketov.edu.kz/mathematics-vestnik/article/view/519.