@misc{indiciae881766c95e78,
  title = {Bedrock geologic map of Massachusetts},
  author = {N. M. Ratcliffe and Peter Robinson and R. S. Stanley},
  year = {1981},
  doi = {10.3133/ofr811327},
  url = {https://pubs.usgs.gov/publication/ofr811327},
  note = {Source identifier: ofr811327}
}