@article{GDZPPN002280051, title = {Differential Invariants in a General Differential Geometry}, journal = {Mathematische Annalen}, volume = {116}, year = {1939}, pages = {310-333}, zbl = {0020.36905}, url = {http://dml.mathdoc.fr/item/GDZPPN002280051} }
MichaI, A.D.; Hyers, D.H. Differential Invariants in a General Differential Geometry. Mathematische Annalen, Tome 116 (1939) pp. 310-333. http://gdmltest.u-ga.fr/item/GDZPPN002280051/