TY  - JOUR
AU  - A. I. Tret'yak
TI  - Necessary conditions for optimality of even order in a
JO  - Doklady Akademii Nauk
PY  - 1991
SP  - 1058
EP  - 1060
VL  - 316
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1991_316_5_a7/
LA  - ru
ID  - DAN_1991_316_5_a7
ER  -