@misc{indiciaeb146f8bd170c,
  title = {Surficial geologic map of parts of Union and Snyder counties, Pennsylvania},
  author = {D. E. Marchand and G.H. Crowl},
  year = {1991},
  doi = {10.3133/i2051},
  url = {https://pubs.usgs.gov/publication/i2051},
  note = {Source identifier: i2051}
}