1. N. N. Bogolyubov, Ukr. Matem. Zh.,2, 3 (1950); Selected Works [in Russian], Vol. 2, Naukova Dumka (1970).
2. E. P. Solodovnikova, A. N. Tavkhelidze, and O. A. Khrustalev, Teor. Mat. Fiz.,10, 162 (1972).
3. E. P. Solodovnikova and A. N. Tavkhelidze, Proceedings of Session of the Section of Nuclear Physics of the Academy of Sciences of the USSR [in Russian], Moscow (1972).
4. A. A. Arkhipov and N. E. Tyurin, Preprint IFVÉ-72-37 [in Russian], Serpukhov (1972).
5. Proceedings of the Seminar on Fundamental Problems of Elementary Particle Theory, Preprint ITF 70-99, Kiev (1970).