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@article{DAN_1970_193_2_a13, author = {V. S. Fedii}, title = {Estimates in the $H_{(s)}$ norms, and hypoellipticity}, journal = {Doklady Akademii Nauk}, pages = {301--303}, publisher = {mathdoc}, volume = {193}, number = {2}, year = {1970}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1970_193_2_a13/} }
V. S. Fedii. Estimates in the $H_{(s)}$ norms, and hypoellipticity. Doklady Akademii Nauk, Tome 193 (1970) no. 2, pp. 301-303. http://geodesic.mathdoc.fr/item/DAN_1970_193_2_a13/