@misc{indiciaeb74d5343e10c,
  title = {Geologic mapping by means of graphic locator},
  author = {David J. Varnes},
  year = {1946},
  doi = {10.3133/cir12},
  url = {https://pubs.usgs.gov/publication/cir12},
  note = {Source identifier: cir12}
}