@misc{indiciae9720ead51e20,
  title = {Coal geology and the future; symposium abstracts and selected references},
  author = {C. B. Cecil and G. D. Stricker},
  year = {1977},
  doi = {10.3133/cir757},
  url = {https://pubs.usgs.gov/publication/cir757},
  note = {Source identifier: cir757}
}