Roumanian oil industry for first half of 1913. 

 - London-GB :   The mining journal,   1913. 
 - página 1072 :   ilustraciones blanco y negro 
 - Irregular 
 - Vol. CIII, no.4081 (Nov. 1913) 
 - The mining journal, Raiway & commercial gazette ;   no.4081 .
 - The mining journal. .