@misc{indiciae049a50c95610,
  title = {The US Geological Survey's national coal resource assessment: The results},
  author = {Leslie F. Ruppert and Mark A. Kirschbaum and Peter D. Warwick and Romeo M. Flores and Ronald H. Affolter and Joseph R. Hatch},
  year = {2002},
  doi = {10.1016/s0166-5162(02)00120-9},
  url = {https://pubs.usgs.gov/publication/70024716},
  note = {Source identifier: 70024716}
}