TY  - JOUR
AU  - K. S. Sibirskii
TI  - Centroaffine invariant center and simple saddle-center conditions for a quadratic differential system
JO  - Doklady Akademii Nauk
PY  - 1985
SP  - 819
EP  - 823
VL  - 285
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1985_285_4_a10/
LA  - ru
ID  - DAN_1985_285_4_a10
ER  -