@misc{indiciaeef7a662d7bbe,
  title = {Coal resources of the United States, January 1, 1974},
  author = {Paul Averitt},
  year = {1975},
  doi = {10.3133/b1412},
  url = {https://pubs.usgs.gov/publication/b1412},
  note = {Source identifier: b1412}
}