TY  - BOOK
AU  - Tryon,F.G.
AU  - Hale,Sydney A.
TI  - Coal in 1919, 1920 and 1921
T2  - Mineral Resources of the United States, 1921-Part II
U1  - 553.2 
PY  - 1923///
CY  - Washington, D.C.
PB  - Government Printing Office
KW  - MINERIA
KW  - CARBON
N1  - Impreso; En biblioteca 2 ejemplares
ER  -