@article{MAT_1963_7_1_a3,
     author = {L. H\"ormander},
     title = {Hypoelliptic differential operators},
     journal = {Matematika},
     pages = {66--78},
     publisher = {mathdoc},
     volume = {7},
     number = {1},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1963_7_1_a3/}
}