@misc{indiciae698ba431696f,
  title = {Map of overdip slopes that can affect landsliding in Allegheny County, Pennsylvania},
  author = {R. P. Briggs},
  year = {1974},
  doi = {10.3133/mf543},
  url = {https://pubs.usgs.gov/publication/mf543},
  note = {Source identifier: mf543}
}