@article{IM2_1983_20_3_a7,
     author = {I. A. Shishmarev},
     title = {On the {Cauchy} problem and $T$-products for hypoelliptic systems},
     journal = {Izvestiya. Mathematics },
     pages = {577--609},
     publisher = {mathdoc},
     volume = {20},
     number = {3},
     year = {1983},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1983_20_3_a7/}
}