@article{SM_1984_47_2_a15,
     author = {N. A. Shananin},
     title = {On local unsolvability and nonhypoellipticity of (pseudo-) differential equations with weighted symbols},
     journal = {Sbornik. Mathematics},
     pages = {541--556},
     year = {1984},
     volume = {47},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1984_47_2_a15/}
}