1. M.D. Perry and G. Mourou, Science 264, 917 (1994)
2. C. Sauteret, G. Mainfray, and G. Mourou, Laser Focus World, October (1990)
3. H. Eichmann; S. Meyer, K. Riepl, C. Momma, and B. Wellegehausen, Phys. Rev. A 50, R2834 (1994)
4. M.B. Gaarde, A. Persson, C.-G. Wahlström, A. L’Huillier, P. Antoine, B. Carré, and S. Svanberg, presented at the conference “Generation and application of ultrashort x-ray pulses” in Pisa, Italy (September 1995)
5. S. Watanabe, K. Konde, Y. Nabekawa, A. Sagisaka, and Y. Koboyashi, Phys. Rev. Lett. 73, 2692 (1994)