Optical spectroscopy of random deformations in elastically-anisotropic crystals containing rare-earth ionsB.Z. Malkin, E.I. Baibekov, N.M. Abishev, D.S. Pytalev, M.N. Popova and M. BettinelliEPJ Web Conf., 132 (2017) 02016DOI: https://doi.org/10.1051/epjconf/201713202016