TY  - JOUR
AU  - V. V. Amel'kin
TI  - On conditions for the existence of limit cycles in two-dimensional autonomous systems of differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1995
SP  - 2070
EP  - 2072
VL  - 31
IS  - 12
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1995_31_12_a15/
LA  - ru
ID  - DE_1995_31_12_a15
ER  -