Kazanko OV, Penkina OE, Golovko OV. Development of a methodology for transitioning from a spectral equation relative to a spatial variable to a differential equation relative to a spectral parameter in the Sturm-Liouville problem for a one-dimensional periodic two-layer photonic crystal. radiophysics [Internet]. 2025Jul.1 [cited 2026Jan.12];(42):55-3. Available from: https://periodicals.karazin.ua/radiophysics/article/view/27758