@misc{indiciae22eb149c9474,
  title = {Stratigraphy of the bituminous coal field of Pennsylvania, Ohio and West Virginia},
  author = {I. C. White},
  year = {1891},
  doi = {10.3133/b65},
  url = {https://pubs.usgs.gov/publication/b65},
  note = {Source identifier: b65}
}