@misc{indiciae81ccc62156e1,
  title = {Seismicity of the United States, 1568-1989 (revised)},
  author = {C. W. Stover and J.L. Coffman},
  year = {1993},
  doi = {10.3133/pp1527},
  url = {https://pubs.usgs.gov/publication/pp1527},
  note = {Source identifier: pp1527}
}