@misc{indiciaee464aa00f7ac,
  title = {New reference materials for nitrogen-isotope-ratio measurements},
  author = {J.K. Bohlke and C. J. Gwinn and T. B. Coplen},
  year = {2007},
  doi = {10.1111/j.1751-908x.1993.tb00131.x},
  url = {https://pubs.usgs.gov/publication/70188275},
  note = {Source identifier: 70188275}
}