Polya, G.  <br/><br/>
How to solve it :  A new aspect of mathematical method / 
G. Polya. 
 - 2nd. ed. 
 - USA :  Penguin Books,  1990. 
 - xxxix, 253 p.  20 cm. 
<br/><br/><label>ISBN: </label>9780140124996 (pbk.) 
<br/><br/><label>LC Class. No.: </label>QA 11   / .P6 1990