1. E. L. Hahn, Phys. Rev.,80, No. 3, 580?594 (1950).
2. B. P. Smolyakov and E. P. Khaimovich, Zh. Eksp. Tekh. Fiz.,76, No. 4, 1303?1308 (1979).
3. V. P. Chekmarev, M. I. Kurkin, and S. I. Goloshchapov, Zh. Eksp. Tekh. Fiz.,76, No. 5, 1675?1684 (1979).
4. Yu. M. Bun'kov and B. S. Dumesh, in: Problems of Magnetic Resonance [in Russian], Nauka, Moscow (1978), pp. 310?327.
5. J. D. Abella, N. A. Kurnit, and S. Hartmann, Phys. Rev.,141, No. 1, 391?411 (1966).