TY - JOUR AU - G. G. Kazaryan AU - V. N. Markaryan TI - Hypoellipticity criteria in terms of power and strength of operators JO - Trudy Matematicheskogo Instituta imeni V.A. Steklova PY - 1979 SP - 128 EP - 142 VL - 150 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/TM_1979_150_a7/ LA - ru ID - TM_1979_150_a7 ER -