TY  - JOUR
AU  - M. I. Voilokov
TI  - A~method of estimating an upper bound of the number of periodic solutions of an autonomous system of two differential equations
JO  - Trudy Matematicheskogo Instituta imeni V.A. Steklova
PY  - 1961
VL  - 16
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/RM_1961_16_3_a7/
LA  - ru
ID  - RM_1961_16_3_a7
ER  -