TY  - JOUR
AU  - O. A. Timoshin
TI  - The best approximation to the operator of the second mixed derivative
JO  - Izvestiya. Mathematics 
PY  - 1998
SP  - 191
EP  - 200
VL  - 62
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_1998_62_1_a5/
LA  - en
ID  - IM2_1998_62_1_a5
ER  -