Khan, David. <br/><br/>
The codebreakers :  the story of secret writing / 
David Khan. 
 - London :   Weidenfeld & Nicolson,   c 1969. 
 - 1164 p. :  ill. ;  22 cm. 
<br/><br/> Includes index. 
<br/><br/>29  29 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Secret writing.
<br/><br/><label>Dewey Class. No.: </label>652.8 / K122c