@misc{indiciae7c37183dccb5,
  title = {The Loma Prieta, California, earthquake of October 17, 1989: Preseismic observations},
  author = {Malcolm J. S. Johnston and Jean A. Olson and David P. Hill and Anthony C. Fraser-Smith and Arman Bernardi and Robert A. Helliwell and Paul R. McGill and O.G. Villard and Robert J. Mueller and Randall A. White and William L. Ellsworth and Evelyn A. Roeloffs and Alan T. Linde and M. T. Gladwin and R. L. Gwyther and R.H.G. Hart and Michael Lisowski and James C. Savage and William H. Prescott and Jerry L. Svarc and Mark Hunter Murray and P.G. Silver and N. J. Valette-Silver and Olga Kolbek},
  year = {1993},
  doi = {10.3133/pp1550c},
  url = {https://pubs.usgs.gov/publication/pp1550C},
  note = {Source identifier: pp1550C}
}