@misc{indiciaea4acaa6daf3d,
  title = {Monitoring soil geochemistry in the urban environment: A comparison of studies in 1972 and 2005 in Denver, Colorado},
  author = {David B. Smith and Karl J. Ellefsen and Ronald G. Garrett and L. Graham Closs},
  year = {2011},
  url = {https://pubs.usgs.gov/publication/70044955},
  note = {Source identifier: 70044955}
}