TY  - JOUR
AU  - A. A. Ligun
TI  - Exact inequalities of Jackson type for periodic functions in space $L_2$
JO  - Matematičeskie zametki
PY  - 1988
SP  - 757
EP  - 769
VL  - 43
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZM_1988_43_6_a5/
LA  - ru
ID  - MZM_1988_43_6_a5
ER  -