Beker, Henry J. <br/><br/>
Secure speech communications  / 
Henry J. Beker, Fred C. Piper. 
 - London :  Academic Press,  cop. 1985. 
 - xi, [1], 267 s. :  il. ;  24 cm. 
<br/><br/><label>ISBN: </label>0120847809 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Kryptografia.