SlyusarchukV. Y. (2010) “Strengthening of the Kneser theorem on zeros of solutions of the equation $u″ + q(t)u = 0$ using one functional equation”, Ukrains’kyi Matematychnyi Zhurnal, 62(12), pp. 1705–1714. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/2993 (Accessed: 4December2024).