1. A. A. Logunov and A. N. Tavkhelidze, Nuovo Cimento,29, 380 (1963).
2. V. Sh. Gogokhiya, D. P. Mavlo and A. T. Filippov, Teor. Mat. Fiz.,27, 323 (1976).
3. V. Sh. Gogokhiya, Teor. Mat. Fiz.,48, 80 (1981).
4. V. Sh. Gogokhiya, D. P. Mavlo, and A. T. Filippov, ?Investigation of solutions of the Logunov-Tavkhelidze quasipotential equation and its modifications,? Preprint R2-9894 [in Russian], JINR, Dubna (1976).
5. K. M. Case, Phys. Rev.80, 797 (1950).