1. 1. P.V.Ionov, V.V.Voronov, V.T.Gabrielyan, Finding of photo-induced change of refraction in ferroelectric lead germinate (in Russian) // 17, (4), p. 1144-1148 (1975).
2. 2. N. Uchida, T. Saku, H. Iwasaki, Electro-optic properties of ferroelectric 5Pb⋅3GeO2single crystal // J. Appl. Phys. 43.p.4933-4936 (1972).
3. 3. V.T.Gabrielyan, P.U.Ionov, K.A.Mikhailina, Growing and some characteristics of monocrystal 5Pb⋅3GeO2(in Russian) // Crystallography 19, p. 176-178 (1974).
4. 4. V.A.Kizel, V.I.Burkov, Gyrotropy of crystals (in Russian), «Nauka», Moscow (1980).
5. 5. W. Krolikowski, M. Cronin-Golomb, Bo Su Chen, Photorefractive effect in ferroelectric lead germanate // App. Phys.Let.57(1) p. 7-9 (1990).