@misc{indiciae5f139b5d7d82,
  title = {Lower middle ordovician of south-central Pennsylvania},
  author = {Lawrence C. Craig},
  year = {1949},
  doi = {10.1130/0016-7606(1949)60[707:lmoosp]2.0.co;2},
  url = {https://pubs.usgs.gov/publication/70215520},
  note = {Source identifier: 70215520}
}