@misc{indiciaeac00bc12a30f,
  title = {County-level estimates of nitrogen and phosphorus from animal manure for the conterminous United States, 2007 and 2012},
  author = {JoAnn M. Gronberg and Terri Arnold},
  year = {2017},
  doi = {10.3133/ofr20171021},
  url = {https://pubs.usgs.gov/publication/ofr20171021},
  note = {Source identifier: ofr20171021}
}