Chow, Shui-Nee <br/><br/>
Normal forms and Bifurcation of planar vector fields 

 - Cambridge  Cambridge University Press  1994 
 - viii,472p.  22 cm. 
<br/><br/><label>ISBN: </label>0521372267 
<br/><br/><label>Dewey Class. No.: </label>515.35,  / D, Cho