Slyusarchuk, V. E. (1996) “Refinement of Kneser theorem on zeros of solutions of the equation $y" + p(x)y = 0$”, Ukrains’kyi Matematychnyi Zhurnal, 48(4), pp. 520-524. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5314 (Accessed: 17May2024).