Bell system technical Jr. vol.19... 1940 

 - New York  Ame.Telephone & Telegraphic Co.  1926 
<br/><br/><label>Subjects--Topical Terms: </label><br/>D66m73:N22
<br/><br/><label>Dewey Class. No.: </label>D66m73:N22  / F2.19