@misc{indiciae66c3e24812b2,
  title = {Reconnaissance bedrock geologic map of the Fitchburg Quadrangle and part of the Ashby Quadrangle, northeast-central Massachusetts},
  author = {J. D. Peper and F.A. Wilson},
  year = {1978},
  doi = {10.3133/mf959},
  url = {https://pubs.usgs.gov/publication/mf959},
  note = {Source identifier: mf959}
}