TY - JOUR AU - S. M. Nikol'skii TI - Approximations of periodic functions by trigonometrical polynomials JO - Trudy Matematicheskogo Instituta imeni V.A. Steklova PY - 1945 SP - 3 EP - 76 VL - 15 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/TM_1945_15_a0/ LA - ru ID - TM_1945_15_a0 ER -