@misc{indiciae5b214c8bb765,
  title = {Trailhead quotas},
  author = {J. W. van Wagtendonk and P.R. Coho},
  year = {1986},
  doi = {10.1093/jof/84.11.22},
  url = {https://pubs.usgs.gov/publication/1007533},
  note = {Source identifier: 1007533}
}