@misc{indiciaef9c1c28a1999,
  title = {Thickness of overburden map, Fairfax Quadrangle, Virginia},
  author = {Arthur E. Nelson},
  year = {1976},
  doi = {10.3133/ofr76612},
  url = {https://pubs.usgs.gov/publication/ofr76612},
  note = {Source identifier: ofr76612}
}