TY  - JOUR
AU  - N. I. Chernykh
TI  - The best approximation of periodic functions by trigonometric polynomials in~$L^2$
JO  - Matematičeskie zametki
PY  - 1967
SP  - 513
EP  - 522
VL  - 2
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZM_1967_2_5_a8/
LA  - ru
ID  - MZM_1967_2_5_a8
ER  -