TY  - RPRT
TI  - Historical review of and current progress in coal-resource estimation in the United States
AU  - G.H. Wood
PY  - 1981
DO  - 10.1130/0016-7606(1981)92<520:hroacp>2.0.co;2
UR  - https://pubs.usgs.gov/publication/70011900
ID  - 70011900
ER  -