1. Mathematical Problems in Classical Physics;Arnold,1994
2. Sur la géometrie différentielle des G-structures;Bernard;Ann. Inst. Fourier, Grenoble,1960
3. Natural tensors on Riemannian manifolds;Epstein;J. Differential Geom.,1975
4. Theory of G-structures, Vol. 1;Fujimoto,1972
5. Transformation Groups in Differential Geometry;Kobayashi,1972