@misc{indiciae3dd0e4e8fc1e,
  title = {Geology of the igneous rocks of Essex County, Massachusetts},
  author = {C. H. Clapp},
  year = {1921},
  doi = {10.3133/b704},
  url = {https://pubs.usgs.gov/publication/b704},
  note = {Source identifier: b704}
}