Wrixon, Fred B. <br/><br/>
Codes, ciphers, and secret languages / 
Fred B. Wrixon. 
 - London :  Harrap,  1989. 
 - 266 p. 
<br/><br/><label>ISBN: </label>0245548807 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Ciphers--History<br/>Cryptography--History