@misc{indiciaecf6a9d7aaaa3,
  title = {Remote sensing and airborne geophysics in the assessment of natural aggregate resources},
  author = {D. H. Knepper and W. H. Langer and S.H. Miller},
  year = {1994},
  doi = {10.3133/ofr94158},
  url = {https://pubs.usgs.gov/publication/ofr94158},
  note = {Source identifier: ofr94158}
}