@misc{indiciae9205702ad64d,
  title = {Bibliography and index of U.S. Geological Survey publications relating to coal, 1882-1970},
  author = {Paul Averitt and Lorreda Lopez},
  year = {1972},
  doi = {10.3133/b1377},
  url = {https://pubs.usgs.gov/publication/b1377},
  note = {Source identifier: b1377}
}