@misc{indiciae826f49653662,
  title = {Preliminary bedrock geologic map of the Lowell-Westford area, Massachusetts},
  author = {Richard H. Jahns and M.E. Willard and Walter S. White},
  year = {1959},
  doi = {10.3133/ofr5970},
  url = {https://pubs.usgs.gov/publication/ofr5970},
  note = {Source identifier: ofr5970}
}