1. A. A. Andronov et al., Infrared Physics, Vol.18, 5/6, 385?393 (1978)
2. V. A. Flyagin et al., IEEE Trans. MTT, Vol. MTT-25, 514?521 (1977)
3. M. A. Moiseev, Radiphysics and Quantum Electronics, Vol.20, 8, 846?849 (1977)
4. S. V. Kolosov and A. A. Kurayev Radio Engineering and electronic Physics, Vol.19, 10, 65?73 (1974)
5. A. A. Kurayev et al., Radio Engineering and Electronic Physics, Vol.19, 5, 96?103 (1974)