@misc{indiciae9b345aea97d2,
  title = {Surficial geologic map of the Pepperell quadrangle, Middlesex County, Massachusetts, and Hillsborough County, New Hampshire},
  author = {Carl Koteff and Richard P. Volckmann},
  year = {1973},
  doi = {10.3133/gq1118},
  url = {https://pubs.usgs.gov/publication/gq1118},
  note = {Source identifier: gq1118}
}