@misc{indiciae4ef7def88e9b,
  title = {Preliminary bedrock geologic map of the Ludlow Quadrangle, Massachusetts},
  author = {G. W. Leo and Peter Robinson and J. D. Peper and D.J. Hall},
  year = {1974},
  doi = {10.3133/ofr74102},
  url = {https://pubs.usgs.gov/publication/ofr74102},
  note = {Source identifier: ofr74102}
}