@misc{indiciae18fd04b90ae8,
  title = {Distribution of the Middle Ordovician Copenhagen formation and its trilobites in Nevada},
  author = {Reuben James Ross and Frederick C. Shaw},
  year = {1972},
  doi = {10.3133/pp749},
  url = {https://pubs.usgs.gov/publication/pp749},
  note = {Source identifier: pp749}
}