Lewin, Ronald. <br/><br/>
The other Ultra / 
Ronald Lewin. 
 - London :  Hutchinson,  1982. 
 - xv, 332 p., [16] p. of plates :  ill. ;  24 cm. 
<br/><br/> Includes index. 
<br/><br/>Bibliography: p. 309-311. 
<br/><br/><label>ISBN: </label>0091474701 :  £10.95 
<br/><br/><label>LCCN: </label>82150842  
<br/><br/><label>Subjects--Topical Terms: </label><br/>World War, 1939-1945--Cryptography.
<br/><br/><label>LC Class. No.: </label>D810.C88  / L58