@misc{indiciae21ebd991179f,
  title = {Bedrock geologic map of the Hampden quadrangle, Massachusetts and Connecticut},
  author = {John D. Peper},
  year = {1977},
  doi = {10.3133/gq1368},
  url = {https://pubs.usgs.gov/publication/gq1368},
  note = {Source identifier: gq1368}
}