@misc{indiciaea751950e14c7,
  title = {Palynological studies of the coals of the Princess Reserve District in northeastern Kentucky},
  author = {Robert M. Kosanke},
  year = {1973},
  doi = {10.3133/pp839},
  url = {https://pubs.usgs.gov/publication/pp839},
  note = {Source identifier: pp839}
}