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2. L. A. Blyumenfel'd, V. V. Voevodskii, and A. G. Semenov, Application of Electronic Paramagnetic Resonance in Chemistry [in Russian]. Novosibirsk (1962).
3. Collection of articles entitled ?Optical Coherent Quantum Generators and Amplifiers? [Russian translation]. IL Press (1963).
4. Proc. IEEE,51, 1 (1963).
5. V. S Zuev and P. G. Kryukov, PTé,188, No. 3 (1963).