@misc{indiciaef66f86d08ab7,
  title = {Some structural features of the Northern Anthracite coal basin, Pennsylvania},
  author = {N. H. Darton},
  year = {1940},
  doi = {10.3133/pp193d},
  url = {https://pubs.usgs.gov/publication/pp193D},
  note = {Source identifier: pp193D}
}