@misc{indiciaea77c0b190c8e,
  title = {Environmental geology, Allegheny County and vicinity, Pennsylvania: Description of a program and its results},
  author = {Reginald Peter Briggs},
  year = {1977},
  doi = {10.3133/cir747},
  url = {https://pubs.usgs.gov/publication/cir747},
  note = {Source identifier: cir747}
}