@misc{indiciaee8b3ad5ea627,
  title = {Symbols for 1:50,000-scale 15-minute quadrangle topographic maps of the United States},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1977},
  doi = {10.3133/70101777},
  url = {https://pubs.usgs.gov/publication/70101777},
  note = {Source identifier: 70101777}
}