@misc{indiciae2d394c828f2c,
  title = {Geologic map database of the Washington DC area featuring data from three 30 x 60 minute quadrangles: Frederick, Washington West, and Fredericksburg},
  author = {Adam M. Davis and C. Scott Southworth and James E. Reddy and J. Stephen Schindler},
  year = {2001},
  doi = {10.3133/ofr01227},
  url = {https://pubs.usgs.gov/publication/ofr01227},
  note = {Source identifier: ofr01227}
}