@misc{indiciae80307eddde0b,
  title = {Maps showing landslides and slopes most susceptible to sliding in parts of the Mars and Valencia 7 1/2-minute quadrangles, Butler County, Pennsylvania},
  author = {John S. Pomeroy},
  year = {1977},
  doi = {10.3133/ofr77818},
  url = {https://pubs.usgs.gov/publication/ofr77818},
  note = {Source identifier: ofr77818}
}