TY - JOUR AU - S. M. Nikol'skii TI - The preservation of class under a differentiable mapping JO - Trudy Matematicheskogo Instituta imeni V.A. Steklova PY - 1971 SP - 327 EP - 336 VL - 112 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/TM_1971_112_a20/ LA - ru ID - TM_1971_112_a20 ER -