@article{MMO_1967_16_a3,
     author = {Yu. V. Egorov},
     title = {Hypoelliptic pseudodifferential operators},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {99--108},
     publisher = {mathdoc},
     volume = {16},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1967_16_a3/}
}