@misc{indiciaedf856b63c7f8,
  title = {The coal fields of Ohio, with a computation of the original coal content of the fields},
  author = {J. A. Bownocker and F. R. Clark},
  year = {1917},
  doi = {10.3133/pp100b},
  url = {https://pubs.usgs.gov/publication/pp100B},
  note = {Source identifier: pp100B}
}