TY  - RPRT
TI  - The US Geological Survey's national coal resource assessment: The results
AU  - Leslie F. Ruppert
AU  - Mark A. Kirschbaum
AU  - Peter D. Warwick
AU  - Romeo M. Flores
AU  - Ronald H. Affolter
AU  - Joseph R. Hatch
PY  - 2002
DO  - 10.1016/s0166-5162(02)00120-9
UR  - https://pubs.usgs.gov/publication/70024716
ID  - 70024716
ER  -