@article{IM2_1974_8_3_a9,
     author = {V. I. Blagodatskikh},
     title = {Sufficient optimality conditions for differential imbeddings},
     journal = {Izvestiya. Mathematics },
     pages = {621--630},
     publisher = {mathdoc},
     volume = {8},
     number = {3},
     year = {1974},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1974_8_3_a9/}
}