Valkenvurg, Van M. E., <br/><br/>
Reference Data for Engineers :  Radio, Electronics, Computer, and Communictions 

 - 8th ed. 
 - Boston :  Newnes,  c1949. 
 - p.:  ill.; 
<br/><br/><label>ISBN: </label>0750670649 
<br/><br/><label>Dewey Class. No.: </label>621.38103  / VAL/REF