@misc{indiciaeac542be1876c,
  title = {Graphic-locator method in geologic mapping},
  author = {David J. Varnes and Tommy L. Finnell and Edwin V. Post},
  year = {1959},
  doi = {10.3133/b1081a},
  url = {https://pubs.usgs.gov/publication/b1081A},
  note = {Source identifier: b1081A}
}