@misc{indiciaeea7af826f7e8,
  title = {Bibliography and index of U.S. Geological Survey publications relating to coal, 1971-1975},
  author = {Flora K. Walker},
  year = {1976},
  doi = {10.3133/cir742},
  url = {https://pubs.usgs.gov/publication/cir742},
  note = {Source identifier: cir742}
}