@article{RM_1985_40_6_a10,
     author = {V. M. Karnaukhov},
     title = {On local hypoellipticity of second-order operators with degenerate {Levi} matrix},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {127--128},
     publisher = {mathdoc},
     volume = {40},
     number = {6},
     year = {1985},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1985_40_6_a10/}
}