@article{MZM_1995_57_6_a0,
     author = {A. D. Bruno and S. Yu. Sadov},
     title = {Formal integral of a~divergence-free system},
     journal = {Matemati\v{c}eskie zametki},
     pages = {803--813},
     publisher = {mathdoc},
     volume = {57},
     number = {6},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1995_57_6_a0/}
}