@misc{indiciaecbdfc5cf5e7e,
  title = {Introduction and summary},
  author = {W. A. Willford and R.A. Bergstedt and W.H. Berlin and N.R. Foster and R.J. Hesselberg and M. J. Mac and D.R.M. Passino and R.E. Reinert and D. V. Rottiers},
  year = {1981},
  url = {https://pubs.usgs.gov/publication/2001426},
  note = {Source identifier: 2001426}
}