TY  - BOOK
AU  - Dumortier,F.,et al
TI  - Bifurcations of planar vector fields: nilpotent singularities & abelian integrals
T2  - Lecture notes in mathematics 1480
SN  - 3540545212
U1  - 6.07 
PY  - 1991///
CY  - Berlin
PB  - Springer
ER  -