@misc{indiciaea2f1508c9ff0,
  title = {Coal resources of Oklahoma},
  author = {James V. A. Trumbull},
  year = {1957},
  doi = {10.3133/b1042j},
  url = {https://pubs.usgs.gov/publication/b1042J},
  note = {Source identifier: b1042J}
}