TY  - RPRT
TI  - Mapping forest canopy gaps using air-photo interpretation and ground surveys
AU  - T.J. Fox
AU  - M. G. Knutson
AU  - R. K. Hines
PY  - 2000
UR  - https://pubs.usgs.gov/publication/1003012
ID  - 1003012
ER  -