@misc{indiciae8c086fa37bd9,
  title = {Research in coal paleobotany since 1943},
  author = {James M. Schopf},
  year = {1949},
  doi = {10.2113/gsecongeo.44.6.492},
  url = {https://pubs.usgs.gov/publication/70215459},
  note = {Source identifier: 70215459}
}