@misc{indiciae31c971845e23,
  title = {GSDIG; a program to determine latitude/longitude location using a microcomputer (IBM-PC or compatible) and digitizer; documentation},
  author = {Gary I. Selner and Cole L. Smith and Richard B. Taylor},
  year = {1988},
  doi = {10.3133/ofr8814a},
  url = {https://pubs.usgs.gov/publication/ofr8814A},
  note = {Source identifier: ofr8814A}
}