1. E. L. Belokoneva and N. V. Belov, Dokl. Akad. Nauk SSSR, 260 (6), 1363 (1981).
2. A. A. Kaminskii, Physics and Spectroscopy of Laser Crystals (Nauka, Moscow, 1986) [in Russian].
3. B. V. Grinev, M. F. Dubovik, and A. V. Tolmachev, Optical Single Crystals of Complex Oxide Compounds (Institute of Single Crystals, Kharkov, 2002) [in Russian].
4. B. V. Mill’, B. A. Maximov, Yu. V. Pisarevsky, et al., IEEE Ultrasonic, Ferroelectrics, and Frequency Control Joint 50th Anniversary Conference, 2004, p. 52.
5. I. A. Andreev, Tekh. Phys. 49 (9), 1101 (2004).