1. E. M. Belenov, V. N. Morozov, and A. N. Oraevskii, Trudy FIAN, 322 (1964).
2. Ya. I. Khanin, Dynamics of Quantum Generators [in Russian], Nauka, Moscow (1975).
3. J. Opt. Soc. Am.,B1 (1985).
4. A. E. Grasyuk and A. N. Oraevskii, Radiotekh. Elektron., No. 9, 527 (1964).
5. A. N. Oraevskii, Molecular Generators [in Russian], Nauka, Moscow (1964).