@misc{indiciae8c98a0c17f9d,
  title = {Resource assessment of the Springfield, Herrin, Danville, and Baker coals in the Illinois Basin},
  author = {Joseph R. Hatch and Ronald H. Affolter},
  year = {2002},
  doi = {10.3133/pp1625d},
  url = {https://pubs.usgs.gov/publication/pp1625D},
  note = {Source identifier: pp1625D}
}