@article{IM2_1988_30_3_a5,
     author = {V. V. Lychagin},
     title = {Singularities of solutions, spectral sequences, and normal forms of {Lie} algebras of vector fields},
     journal = {Izvestiya. Mathematics },
     pages = {549--575},
     publisher = {mathdoc},
     volume = {30},
     number = {3},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1988_30_3_a5/}
}