TY  - RPRT
TI  - Geologic mapping of tunnels using photogrammetry--camera and target positioning
AU  - Jeffrey A. Coe
AU  - Keld S. Dueholm
PY  - 1991
DO  - 10.3133/ofr9049
UR  - https://pubs.usgs.gov/publication/ofr9049
ID  - ofr9049
ER  -