1. G. de Vaucouleurs and W. L. Peters,Astrophys. J. 287, 1?16 (1984).
2. P. Lubin, T. Villela, G. Epstein, and G. Smoot,Astrophys. J. 298, L1?L5 (1985).
3. M. A. Oliver,Found. Phys. 21, 665?690 (1991).
4. C. Truesdell and W. Noll, ?The non-linear field theories of mechanics?, inEncyclopedia of Physics, Vol. III/3, S. Flügge, ed. (Springer, Berlin, 1965).
5. H. Minkowski,Nachr. Ges. Wiss. Göttingen 21, 53?111 (1908).