@misc{indiciaec33ffeec1260,
  title = {Mapping forest canopy gaps using air-photo interpretation and ground surveys},
  author = {T.J. Fox and M. G. Knutson and R. K. Hines},
  year = {2000},
  url = {https://pubs.usgs.gov/publication/1003012},
  note = {Source identifier: 1003012}
}