Rupert, Raphael. <br/><br/>
A hidden world / 
edited by Anthony Rhodes. 
 - London :  Collins,  1963. 
 - 223 p. ;  22 cm. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Cryptography --History.  <br/>Cryptography.
<br/><br/><label>Dewey Class. No.: </label>652.8  / RUH 1963