@misc{indiciae7370c0fe3d3f,
  title = {Periodicity in extinction},
  author = {Sepkoski, J. J. Jr and Sepkoski JJ, J. r.},
  year = {1987},
  url = {https://ntrs.nasa.gov/citations/20040120342},
  note = {Source identifier: 20040120342}
}