@misc{indiciae03fb0804d532,
  title = {Geologic utility of small-scale airphotos},
  author = {Malcolm Mallory Clark},
  year = {1969},
  doi = {10.3133/ofr6940},
  url = {https://pubs.usgs.gov/publication/ofr6940},
  note = {Source identifier: ofr6940}
}