@misc{indiciaec513c674c8d6,
  title = {Preserving Native American petroglyphs on porous sandstone},
  author = {D.A. Grisafe},
  year = {2017},
  doi = {10.1080/2052546.1996.11931813},
  url = {https://pubs.usgs.gov/publication/70018632},
  note = {Source identifier: 70018632}
}