by Kamenskaya, S. A., Kislyakov, A. G., Krotikov, V. D., Naumov, A. I., Nikonov, V. N., Porfir'ev, V. A., Plechkov, V. M., Strezhneva, K. M., Troltskii, V. S., Fedoseev, L. I., Lubyako, L. V., Sorokina, E. P.
Published in Radiophysics and quantum electronics (1966)