TY  - JOUR
AU  - S. P. Tokarev
TI  - Smooth equivalence of systems of differential equations on the plane in the case of a structurally unstable focus
JO  - Differencialʹnye uravneniâ
PY  - 1977
SP  - 892
EP  - 897
VL  - 13
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1977_13_5_a11/
LA  - ru
ID  - DE_1977_13_5_a11
ER  -