TY  - JOUR
AU  - L. A. Cherkas
TI  - Conditions for the center for a certain equation
JO  - Differencialʹnye uravneniâ
PY  - 1977
SP  - 271
EP  - 275
VL  - 13
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1977_13_2_a4/
LA  - ru
ID  - DE_1977_13_2_a4
ER  -