@misc{indiciae5a04ece77a3f,
  title = {SPECtrum Processing Routines User's Manual Version 3 (program SPECPR)},
  author = {Roger N. Clark},
  year = {1993},
  doi = {10.3133/ofr93595},
  url = {https://pubs.usgs.gov/publication/ofr93595},
  note = {Source identifier: ofr93595}
}