@misc{indiciae4bfa91fc3d8b,
  title = {Preliminary surficial geologic and materials maps of the Pepperell quadrangle, Massachusetts-New Hampshire},
  author = {Carl Koteff and R.P. Volckmann},
  year = {1972},
  doi = {10.3133/ofr72213},
  url = {https://pubs.usgs.gov/publication/ofr72213},
  note = {Source identifier: ofr72213}
}