@article{MZM_1991_49_2_a4,
     author = {M. Ya. Zhitomirskii},
     title = {Normal forms of germs of smooth distributions},
     journal = {Matemati\v{c}eskie zametki},
     pages = {36--44},
     year = {1991},
     volume = {49},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_49_2_a4/}
}