TY  - JOUR
AU  - A. A. Bel'kovich
TI  - On the existence of invariant tori for a periodic Hamiltonian system having some of characteristic indices with nonzero real part
JO  - Differencialʹnye uravneniâ
PY  - 1987
SP  - 192
EP  - 198
VL  - 23
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1987_23_2_a1/
LA  - ru
ID  - DE_1987_23_2_a1
ER  -