Amplifiers and heterodynes ... 
 Heterodynes, Amplifiers and 
Prepared in the Office of the chief signal officer, December, 1921. 
 - Washington,  Govt. Print. Off.,  1922. 
 - v, 38 p.  plates, diagrs.  23 cm. 
 - Radio communication pamphlet  no. 9 .
<br/><br/> On verso of t.-p.: War department. Document no. 1092. Office of the Adjutant General. 
<br/><br/><label>LCCN: </label>war22000071  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Radio.
<br/><br/><label>LC Class. No.: </label>TK5707  / .U6 no. 9