@misc{indiciae1b6952cd90c3,
  title = {Determination of niobium in rocks by an isotope dilution spectrophotometric method},
  author = {L. P. Greenland and E.Y. Campbell},
  year = {1970},
  doi = {10.1016/s0003-2670(01)80014-3},
  url = {https://pubs.usgs.gov/publication/70009960},
  note = {Source identifier: 70009960}
}