@misc{indiciae9209e8e9194f,
  title = {Contour map of the bedrock surface, Greenfield Quadrangle, Massachusetts},
  author = {C.J. Londquist and B. P. Hansen},
  year = {1974},
  doi = {10.3133/mf629a},
  url = {https://pubs.usgs.gov/publication/mf629A},
  note = {Source identifier: mf629A}
}