TY  - JOUR
AU  - V. E. Chernyshev
TI  - The existence of saddle periodic solutions of Duffing's equation without dissipation
JO  - Differencialʹnye uravneniâ
PY  - 1977
SP  - 1145
EP  - 1148
VL  - 13
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1977_13_6_a25/
LA  - ru
ID  - DE_1977_13_6_a25
ER  -