Coşkun, Haskiz, and Ayşe Kabataş. “Asymptotic Approximations of Eigen-Functions for Regular Sturm-Liouville Problems With Eigenvalue Parameter in the Boundary Condition for Integrable Potential”. Mathematica Scandinavica 113, no. 1 (September 1, 2013): 143–160. Accessed July 24, 2026. https://journals.msp.org/mscand/article/view/442.