@article{SJIM_2019_22_4_a7,
     author = {H. A. Petrosyan},
     title = {On the properties of the symbols of one class of hypoelliptic equations},
     journal = {Sibirskij \v{z}urnal industrialʹnoj matematiki},
     pages = {81--88},
     publisher = {mathdoc},
     volume = {22},
     number = {4},
     year = {2019},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SJIM_2019_22_4_a7/}
}