@misc{indiciae04b5f3a7b911,
  title = {Chemical analyses of soils and other surficial materials of the conterminous United States},
  author = {Josephine G. Boerngen and Hansford T. Shacklette},
  year = {1981},
  doi = {10.3133/ofr81197},
  url = {https://pubs.usgs.gov/publication/ofr81197},
  note = {Source identifier: ofr81197}
}