@misc{indiciae49933078d356,
  title = {Black and white photographic catalog of geologic/geomorphologic phenomena},
  author = {J.K. McGregor},
  year = {1989},
  doi = {10.3133/ofr89493},
  url = {https://pubs.usgs.gov/publication/ofr89493},
  note = {Source identifier: ofr89493}
}