Andreescu, Titu and Feng, Zuming <br/><br/>
A path to combinatorics for undergraduates  counting strategies 

 - Boston  Birkhauser Verlag  2004 
 - xviii, 228p. Bibl. Index. 
<br/><br/>  
<br/><br/><label>ISBN: </label>0817642889 
<br/><br/><label>Dewey Class. No.: </label>511.6  / An558.PC