No. 1 electronic switching system 

 - America:   American Telephone and Telegraph Company,   1964 
 - 2191p. 
 - Monograph 4853 .
<br/><br/><label>Subjects--Topical Terms: </label><br/>Switching system
<br/><br/><label>Subjects--Index Terms: </label>Network frames 
<br/><br/><label>Universal Decimal Class. No.: </label>621.326.5  / K4.1