1. W. Misner, K. S. Thorne, and J. A. Wheeler,Gravitation (Freeman, San Francisco, 1973), pp. 169 and 228.
2. H. Flanders,Differential Forms with Applications to the Physical Sciences (Dover, New York, 1989), p. 146.
3. L. A. Cordero, C. T. J. Dodson, and M. de Léon,Differential Geometry of Frame Bundles (Kluwer, Dordrecht, 1989).
4. é. Cartan,La Méthode du Repére Mobile, la Théorie des Groupes Continues et las Espaces Generalisées (Herman, Paris, 1935).
5. J. G. Vargas,Found. Phys. 22, 507 (1992).