1. A. A. Logunov and A. N. Tavkhelidze, Nuovo Cimento,29, 380 (1963).
2. V. G. Kadyshevksy, Nucl. Phys. B,6, 125 (1968).
3. V. G. Kadyshevskii and A. N. Tavkhelidze, in: Problems of Theoretical Physics (Dedicated to N. N. Bogolyubov on His Sixtieth Birthday) [in Russian], Nauka, Moscow (1969), pp. 261?277.
4. N. B. Skachkov and I. L. Solovtsov, Yad. Fiz.,30, 1079 (1979).
5. V. N. Kapshai, A. D. Linkevich, V. I. Savrin, and N. B. Skachkov, Teor. Mat. Fiz.,53, 388 (1982).