TY  - BOOK
AU  - Dumortier Freddy
TI  - Bifurcations of planar vector feilds: Nilpotent singularities and abelian
U1  - 515.35 
PY  - 1991///
CY  - Berliln
PB  - Springer Verlag
KW  - Bircations
KW  - Differential equations
KW  - Vector
ER  -