Sinha, Umesh <br/><br/>
Telephony 

 - New Delhi  Satya Prakashan  1999 
 - p.204 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Telephony<br/>Telephone Relays
<br/><br/><label>Dewey Class. No.: </label>621 S617T