Haldane, R. A. <br/><br/>
The hidden world / 
R. A. Haldane 
 - London :  R. Hale,  1976 
 - 207 p. ;  23 cm. 
<br/><br/> Includes index 
<br/><br/><label>ISBN: </label>0709153511 :  USD 3.80 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Cryptography--History
<br/><br/><label>Dewey Class. No.: </label>001.543609