TY  - JOUR
AU  - V. S. Nustrov
TI  - The periodic solutions of systems that are close to nonlinear systems in the case of principal resonance
JO  - Izvestiâ vysših učebnyh zavedenij. Matematika
PY  - 1970
SP  - 63
EP  - 69
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IVM_1970_3_a9/
LA  - ru
ID  - IVM_1970_3_a9
ER  -