I. S. Kachur, V. S. Kurnosov, and V. G. Piryatinskaya, Inversion of exchange interaction sign of Nd³⁺ excited states and its manifestation in optical absorption spectra of NdFe₃(BO₃)₄ crystal, Low Temp. Phys. 50, 425–427, (2024) [Fiz. Nyzk. Temp. 50, 465–468, (2024)] DOI: https://doi.org/10.1063/10.0025636.