1. Yu. B. Rumer and A. I. Fet, Teor. Mat. Fiz.,9, 203 (1971).
2. V. G. Konopel'chenkó, Preprint [in Russian], Institute of Nuclear Physics, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk (1972).
3. Yu. B. Rumer and A. I. Fet, Theory of Unitary Symmetry [in Russian], Moscow (1970).
4. Tsu Yao, J. Math. Phys.,8, 1931 (1967).
5. Tsu Yao,ibid.,9, 1615 (1968).