V. A. Mikhailets and A. Goriunov, “Regularization of singular Sturm-Liouville equations”, MFAT, vol. 16, no. 2, pp. 120–130, Jun. 2010, Accessed: Dec. 16, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/445