@misc{indiciaeb04bc97fa560,
  title = {Surface materials map of the Vienna Quadrangle, Virginia-Maryland},
  author = {A.J. Froelich},
  year = {1976},
  doi = {10.3133/ofr76533},
  url = {https://pubs.usgs.gov/publication/ofr76533},
  note = {Source identifier: ofr76533}
}