@misc{indiciae786558b6df33,
  title = {Preliminary map showing the distribution and thickness of sandstone in the lower member of the Pittsburgh Formation, southwestern Pennsylvania and northern West Virginia},
  author = {J.B. Roen and D.F. Kreimeyer},
  year = {1973},
  doi = {10.3133/mf529},
  url = {https://pubs.usgs.gov/publication/mf529},
  note = {Source identifier: mf529}
}