D.A. Zazymkina, I.I. Usmanov, S.I. Chentsov, S.V. Kuznetsov, A.A. Aleksandrov, V.S. Sedov, A.K. Martyanov, I.A. Tyazhelov, V.S. Krivobok. Fine structure of emission spectra and crystal field parameters for Er3+ ions in NaGdF4 cubic modification. Journal of Luminescence V.299, 2026, 122157 doi.org/10.1016/j.jlumin.2026.