@misc{indiciae52e0a055631f,
  title = {Bedrock geologic map of the Marblehead North quadrangle, Essex County, Massachusetts},
  author = {William H. Dennen},
  year = {1991},
  doi = {10.3133/gq1693},
  url = {https://pubs.usgs.gov/publication/gq1693},
  note = {Source identifier: gq1693}
}