@misc{indiciaec6c52f33baec,
  title = {Essential elements and soil amendments for plants; sources and use for agriculture},
  author = {R. C. Severson and Hansford T. Shacklette},
  year = {1988},
  doi = {10.3133/cir1017},
  url = {https://pubs.usgs.gov/publication/cir1017},
  note = {Source identifier: cir1017}
}