1. For a review,F. W. Hehl, P. von der Heyde, G. D. Kerlick andJ. M. Nester:Rev. Mod. Phys.,48, 393 (1976).
2. K. Hayashi andT. Shirafuji:Prog. Theor. Phys.,64, 866 (1980).
3. M. Mathisson:Acta Phys. Pol.,6, 163 (1937);A. Papapetrou:Proc. R. Soc. London, Ser. A,209, 248 (1951);W. G. Dixon:Nuovo Cimento,34, 317 (1964);P. B. Yasskin andW. R. S. Stoeger:Phys. Rev. D,21, 2081 (1980). See also,A. Trautman:Bull. Acad. Pol. Sci., Ser. Sci., Math., Astron. Phys.,20, 895 (1972);I. Bailey andW. Israel:Commun. Math. Phys.,42, 65 (1975).
4. S. Hojman:Phys. Rev. D,18, 2714 (1978).
5. F. W. Hehl:Phys. Lett. A,36, 225 (1971);K. Hayashi andT. Shirafuji:Prog. Theor. Phys.,64, 883 (1980);J. Audretsch:Phys. Rev. D,24, 1470 (1981).