Nayfeh, A.H <br/><br/>
Perturbation methods 
A.H. Nayfeh 
 - New York  Springer  1973 
 - xii  425 
 - Series in pure & applied mathematics .
<br/><br/><label>ISBN: </label>0471630594 
<br/><br/><label>Dewey Class. No.: </label>4.04+11.07  / NAYF