@misc{indiciaee7ec24d9e758,
  title = {Geologic map of the Loudoun County portion of the Middleburg Quadrangle, Virginia},
  author = {S.W. Kline and P. T. Lyttle and A.J. Froelich},
  year = {1990},
  doi = {10.3133/ofr90641},
  url = {https://pubs.usgs.gov/publication/ofr90641},
  note = {Source identifier: ofr90641}
}