Technical Paper. 

 - Washington DC :  Bureau of Mines,  1915- 
 - n. :  il. ;  23,5 cm 
 - Frecuencia irregular 
 - En biblioteca años 1915-1941. 
<br/><br/> no.576(1937) Bibliography of United States. Bureau of Mines Investigation on coal and its products 1910-35. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Metodología<br/>Minería