STUPKA, A. A. Frequencies of Long-Wave Phonon-Polaritons and Optical Phonons in Diatomic Ionic Crystals. Ukrainian Journal of Physics, [S. l.], v. 59, n. 8, p. 793, 2018. DOI: 10.15407/ujpe59.08.0793. Disponível em: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2018512. Acesso em: 17 aug. 2022.