@misc{indiciae51de8cf8a57e,
  title = {Multiple microtektite horizons in upper Eocene marine sediments: No evidence for mass extinctions},
  author = {G. Keller and Steven L. D’Hondt and T.L. Vallier},
  year = {1983},
  doi = {10.1126/science.221.4606.150},
  url = {https://pubs.usgs.gov/publication/70011256},
  note = {Source identifier: 70011256}
}