@misc{indiciae559fd89c6559,
  title = {Surface-mining modeling for USGS coal assessments},
  author = {Paul E. Pierce},
  year = {2021},
  doi = {10.3133/ofr20211059},
  url = {https://pubs.usgs.gov/publication/ofr20211059},
  note = {Source identifier: ofr20211059}
}