1. P. Mulser, R. Sigel and S. Witkowski, Physics Rep. (Section C of Phys. Lett.) 6, No. 3 (1973), 187, North-Holland Publishing Company
2. D.W. Forslund, J.M. Kindel and E.L. Lindman, Phys. Rev. Lett. 3o, 739 (1973) and many references contained therein to earlier work on this subject
3. J.L. Bobin, M. Decroisette, B. Meyer and C. Vitel, Phys. Rev. Lett. 3o (1973) 594;
4. K. Boyer, Progress Report, Laser Program at LASL, LA-5251-PR (1973), see also ref. /20–21/
5. V.P. Silin, Sov. Phys. JETP 21 (1965) 1127;