M. P. Trubitsyn, M. D. Volnyanskii, A. Yu. Kudzin, B. Ashim, “Critical ESR line broadening in $\mathrm{Li}_{2}\mathrm{Ge}_{7}\mathrm{O}_{15}:\mathrm{Mn}^{2+}$ crystals near the ferroelectric phase transition”, Fizika Tverdogo Tela, 34:6 (1992), 1746–1752
