TY  - JOUR
AU  - V. A. Yakubovich
TI  - A frequency theorem for periodic systems
JO  - Doklady Akademii Nauk
PY  - 1986
SP  - 70
EP  - 73
VL  - 287
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1986_287_1_a15/
LA  - ru
ID  - DAN_1986_287_1_a15
ER  -