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, [S. l.], v. 106, n. 2, p. 83–92, 2022. DOI: 10.31489/2022m2/83-92. Disponível em: http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/519. Acesso em: 4 sep. 2025.