TY  - JOUR
AU  - A. G. Surkov
TI  - Sharp bounds for characteristic indices of second-order linear systems with bounded perturbations
JO  - Differencialʹnye uravneniâ
PY  - 1984
SP  - 792
EP  - 797
VL  - 20
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1984_20_5_a5/
LA  - ru
ID  - DE_1984_20_5_a5
ER  -