@misc{indiciaeb921d3ba4249,
  title = {Reconnaissance of selected minor elements in surface waters of the United States, October 1970},
  author = {W. H. Durum and John David Hem and Sumner Griggs Heidel},
  year = {1971},
  doi = {10.3133/cir643},
  url = {https://pubs.usgs.gov/publication/cir643},
  note = {Source identifier: cir643}
}