@misc{indiciaebf8a0bf16bf4,
  title = {External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network during 1990},
  author = {M.A. Nilles and J.D. Gordon and T. C. Willoughby and L.J. Schroder},
  year = {1993},
  doi = {10.3133/wri924101},
  url = {https://pubs.usgs.gov/publication/wri924101},
  note = {Source identifier: wri924101}
}