TY  - JOUR
AU  - A. V. Kolushov
TI  - Differentiability of the best approximation operator
JO  - Matematičeskie zametki
PY  - 1981
SP  - 577
EP  - 596
VL  - 29
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZM_1981_29_4_a10/
LA  - ru
ID  - MZM_1981_29_4_a10
ER  -