Sub-diffractional cavity modes of terahertz hyperbolic phonon polaritons in tin oxide oleh Flávio H. Feres, Rafael A. Mayer, Lukas Wehmeier, Francisco C. B. Maia, E. R. Viana, Angelo Malachias, Hans A. Bechtel, J. Michael Klopf, Lukas M. Eng, Susanne C. Kehr, J. C. González, Raul O. Freitas, Ingrid D. Barcelos