Kahn, David. <br/><br/>
Code breakers  the story of secret writing 
by David Kahn 
 - New York  MacMillan  1967 
 - xvi, 1164p. 
<br/><br/><label>LCCN: </label>63-16109 
<br/><br/><label>Dewey Class. No.: </label>001.5436  / N67