1. See, for example,J. Jauch andF. Rohrlich:Theory of Photons, and Electrons, appendix 2 (Cambridge, Mass., 1955).
2. The use of Cartan’s technique of exterior differentials, connection and curvature forms, etc., might appreciably shorten and simplify this labor. See, for example,C. Misner, K. Thorne andJ. Wheeler:Gravitation, Part III (San Francisco, Cal., 1973).
3. E. P. Wigner:Ann. Math.,40, 149 (1939);V. Bargmann andE. P. Wigner:Proc. Nat. Acad. Sci.,34, 211 (1948).
4. seeJ. A. Schouten:Ann. Inst. H. Poincaré,5, 51 (1935). An advantage of this system is that all equations are covariant against any change of frame; holonomic and nonholonomic frames are treated in a unified manner.
5. R. L. Ingraham:Nuovo Cimento,43, 368, 483 (1966).(see, say,M. Hamermesh:Group Theory (New York, N. Y., 1964), p. 80, 81). (see, say,M. Hamermesh:Group Theory (New York, N. Y., 1964), p. 80, 81).