Gomilko, A. M., and V. N. Pivovarchik. “Parameter Dependent Estimates for Solutions of Sturm-Liouville Equation”. Methods of Functional Analysis and Topology 6, no. 4 (December 25, 2000): 26–42. Accessed December 17, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/130.