@misc{indiciaeac29355a0eea,
  title = {Geology and coal resources of the Henryetta mining district, Okmulgee County, Oklahoma},
  author = {R.J. Dunham and James V. A. Trumbull},
  year = {1955},
  doi = {10.3133/b1015f},
  url = {https://pubs.usgs.gov/publication/b1015F},
  note = {Source identifier: b1015F}
}