Ballard, William C. <br/><br/>
Elements of radio telephony 

 - 2a ed. 
 - New York  McGraw-hill Book Company  1923 
 - 140 p.  ilus. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>RADIOTELEFONIA
<br/><br/><label>Universal Decimal Class. No.: </label>A/621.3845/B18