@misc{indiciaebe493534c6bc,
  title = {Baked shale and slag formed by the burning of coal beds},
  author = {G. Sherburne Rogers},
  year = {1918},
  doi = {10.3133/pp108a},
  url = {https://pubs.usgs.gov/publication/pp108A},
  note = {Source identifier: pp108A}
}