The World Book Encyclopedia,"W-X-Y-Z" Volume 21 

 - Chicago, USA  World Book, Inc.  1994 
 - 618 pages 
<br/><br/><label>ISBN: </label>0716600943 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Reference works
<br/><br/><label>Index Terms--Genre/Form: </label><br/>General encyclopedias
<br/><br/><label>Universal Decimal Class. No.: </label>030  / T-44