KazankoО.; PenkinaО.; BUTENKO, V.; HOLOVKO, O. Research and determination of the 1st and 2nd derivatives of the component terms of the dispersion equation for a flat two-layer one-dimensional periodic photonic crystal. Visnyk of V.N. Karazin Kharkiv National University, series “Radio Physics and Electronics”, n. 40, p. 29-41, 24 Jun. 2024.