TY  - JOUR
AU  - P. V. Al'brecht
TI  - Differentiable operators of nearly best approximation
JO  - Izvestiya. Mathematics 
PY  - 1999
SP  - 631
EP  - 647
VL  - 63
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_1999_63_4_a0/
LA  - en
ID  - IM2_1999_63_4_a0
ER  -