Winterbotham, Frederick William. <br/><br/>
The Ultra secret 
F. W. Winterbotham. 
 - 1st U.S. ed. 
 - New York  Harper & Row  c1974. 
 - xiii, 199 p.  22 cm. 
<br/><br/><label>ISBN: </label>0060146788  8.95 
<br/><br/><label>LCCN: </label>74007826 //r892 
<br/><br/><label>Subjects--Personal Names: </label><br/>Winterbotham, Frederick William.
<br/><br/><label>Subjects--Topical Terms: </label><br/>World War--Cryptography.<br/>World War--Personal narratives, British.<br/>World War--Secret service--Great Britain.
<br/><br/><label>LC Class. No.: </label>D810.C88  / W56 1974 
<br/><br/><label>Dewey Class. No.: </label>940.54/86/41