Copper for earthing. 

 - London :  Copper Development Association,  1938. 
 - 56 p. 
<br/><br/> "C. D. A. publication no. 30." 
<br/><br/>
<br/><br/><label>Subjects--Topical Terms: </label><br/>Copper.<br/>Electric currents--Grounding.<br/>MCE
<br/><br/><label>Dewey Class. No.: </label>621.319  / COP