@misc{indiciae16cceb8758b1,
  title = {Background geochemistry of some rocks, soils, plants, and vegetables in the conterminous United States, with sections on field studies},
  author = {J. J. Connor and H.T. Shacklette and R.J. Ebens and J. A. Erdman and A.T. Miesch and R.R. Tidball and H. A. Tourtelot},
  year = {1975},
  doi = {10.3133/pp574f},
  url = {https://pubs.usgs.gov/publication/pp574F},
  note = {Source identifier: pp574F}
}