1. R. C. Hollins, Nonlinear Opt. 27(1–4), 1 (2001).
2. K. N. Nashold and D. P. Walter, J. Opt. Soc. Am. B 12, 1228 (1995).
3. J. W. Perry, S. Barlow, J. E. Ehrlich, et al., Nonlinear Opt. 21, 225 (1999).
4. V. V. Danilov, E. N. Sosnov, O. V. Chistyakova, et al., Nonlinear Opt. 27, 279 (2001).
5. D. Vincent, Appl. Opt. 40(36), 6646 (2001).