V. V. Eremenko, V. I. Fomin, and V. S. Kurnosov, Phonon-assisted anti-Stokes excitation of the fluorescence of Mn²⁺ ions in the CsMnCl₃ ּ 2H₂O crystal, Low Temp. Phys. 26, (2000) [Fiz. Nizk. Temp. 26, 658-663, (2000)] DOI: https://doi.org/10.1063/1.1306402.