1. V.Yu. Baranov, V.M. Borisov, A.A. Vedenov, S.V. Drobyazko, V.N. Knizhnikov, A.P. Napartovich, V.G. Niz’ev, A.P. Strel’tsov, in Preprint No. 2248 (in Russian) (Institute of Atomic Energy, Moscow, 1972
2. V.N. Karnyushin, A.N. Malov, R.I. Soloukhin, Kvantovaya Elektron. (Moscow) 5, 555 (1978);
3. Sov. J. Quantum Electron. 8, 319 (1978)
4. H. Seguin, J. Tulip, The article you requested is currently in production and will be available online at a later date. Appl. Phys. Lett. 21, 414 (1972)
5. A.I. PavlovskiT, V.S. Bosamykin, V.I. Karelin, V.S. Nikol???skii. Kvantovaya Elektron. (Moscow) 3, 601 (1976);