@misc{indiciae7059adecaa3c,
  title = {Preliminary bedrock geologic map of the Marblehead North Quadrangle, Massachusetts},
  author = {William H. Dennen},
  year = {1975},
  doi = {10.3133/ofr75543},
  url = {https://pubs.usgs.gov/publication/ofr75543},
  note = {Source identifier: ofr75543}
}