1. M. P. Petrov, S. I. Stepanov, A. V. Khomenko, Photorefractive Crystals in Coherent Optics [in Russian], Nauka, Saint Petersburg (1992).
2. K. Peithmann, A. Wiebrock, and K. Buse, Appl. Phys., 68, 777 (1999).
3. D. Kip, J. Hukriede, and E. Krätzig, Phys. Status Solidi, A168, R3 (1998).
4. D. Kip, Appl. Phys., B67, 131 (1998).
5. D. Kip, B. Kemper, I. Nee, et al., Appl. Phys., B65, 511 (1997).