Ramazanova, K. (2015) “On the existence of focal and conjugate points of half-linear second-order differential equation on a given interval”, Bulletin of the Karaganda University. Mathematics Series, 77(1), pp. 72–78. Available at: http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/14 (Accessed: 26 August 2025).