@misc{indiciae51b6146d2961,
  title = {Preparation, homogenization, and storage of earth standards used and distributed by the International Humic Substances Society},
  author = {W. L. Campbell and Mollie Malcolm},
  year = {1985},
  doi = {10.1016/0146-6380(85)90060-9},
  url = {https://pubs.usgs.gov/publication/70013034},
  note = {Source identifier: 70013034}
}