V. A. Franiv, Z. Czapla, S. Dacko, A. V. Franiv, and O. S. Kushnir, “Structural Transformations in Tl4HgI6 and Tl4CdI6 Crystals as Evidenced by Dielectric Properties and Conductivity”, Ukr. J. Phys., vol. 59, no. 11, p. 1078, Oct. 2018.