@misc{indiciae060a917be617,
  title = {Bibliography and index of U.S. Geological Survey publications relating to coal, January 1971-June 1974},
  author = {Flora K. Walker},
  year = {1975},
  doi = {10.3133/cir709},
  url = {https://pubs.usgs.gov/publication/cir709},
  note = {Source identifier: cir709}
}