A. M. Gomilko and V. N. Pivovarchik, “Asymptotics of Solutions of the Sturm–Liouville Equation with Respect to a Parameter”, Ukr. Mat. Zhurn., vol. 53, no. 6, pp. 742–757, Jun. 2001, Accessed: Apr. 23, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4297