@misc{indiciaeca76fbaa51d0,
  title = {Determination of niobium in the parts per million range in rocks},
  author = {F. S. Grimaldi},
  year = {2002},
  doi = {10.1021/ac60157a035},
  url = {https://pubs.usgs.gov/publication/70010620},
  note = {Source identifier: 70010620}
}