@misc{indiciae140ee262b0b5,
  title = {Directivity in NGA earthquake ground motions: Analysis using isochrone theory},
  author = {P. Spudich and B.S.J. Chiou},
  year = {2008},
  doi = {10.1193/1.2928225},
  url = {https://pubs.usgs.gov/publication/70000553},
  note = {Source identifier: 70000553}
}