R. S. Brezvin, P. A. Shchepanskyi, A. O. Shapravskyi, V. Yo. Stadnyk, M. Ya. Rudysh, and N. Y. Ftomyn, Refractometry of β-modification LiNH₄SO₄ crystals with an admixture of Mn²⁺ and Cu²⁺, Low Temp. Phys. 50, 911–916, (2024) [Fiz. Nyzk. Temp. 50, 1012–1017, (2024)] DOI: https://doi.org/10.1063/10.0028639.