Roussarie, F., Dumortier <br/><br/>
Bifurcations of planar vector fields: nilpotent singularities and abelian integrals 

 - Berlin  Springer-Verlag  1991 
 - 226p, 22 cm. 
 - Lecture notes in mathematics .
<br/><br/><label>Dewey Class. No.: </label>512.55,  / D, um