TY  - JOUR
AU  - L. A. Cherkas
TI  - Two remarks with respect to conditions for a center
JO  - Differencialʹnye uravneniâ
PY  - 1981
SP  - 1709
EP  - 1712
VL  - 17
IS  - 9
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1981_17_9_a26/
LA  - ru
ID  - DE_1981_17_9_a26
ER  -