Bennett, Ralph. <br/><br/>
Intelligence investigations :  how ultra changed history / 
collected papers of Ralph Bennett. 
 - London :  Frank Cass,  1996. 
 - 203 p. :  ill. ;  22 cm. 
<br/><br/>Includes index. 
<br/><br/><label>ISBN: </label>071464742X  RM233.70 
<br/><br/><label>Subjects--Topical Terms: </label><br/>World War, 1939-1945--Military intelligence.<br/>World War, 1939-1945--Cryptography.