1. A. A. Blistanov, Crystals of Quantum and Nonlinear Optics [in Russian], MISIS, Moscow (2000).
2. C. Jousseaume, A. Kahn-Harari, D. Vivien, et al., J. Mater. Chem., 12, 1525 (2002).
3. A. Bensalah, Y. Guyot, M. Ito, et al., Optical Mater., 26, 375 (2004).
4. E. V. Makhonina, V. S. Pervov, and V. S. Dubasova, Chemistry Advances, 73, 1075 (2004).
5. Yu. A. Pyatenko and N. M. Chernitsova, Izv. Akad. Nauk SSSR, Ser. Geol., No. 4, 67 (1990).