@misc{indiciae19f37ffc8d2b,
  title = {Microscopic studies of uraniferous coal deposits},
  author = {James Morton Schopf and Ralph Joseph Gray},
  year = {1954},
  doi = {10.3133/cir343},
  url = {https://pubs.usgs.gov/publication/cir343},
  note = {Source identifier: cir343}
}