TY  - RPRT
TI  - Topographic mapping status and progress of operations: (7 1/2- and 15-minute series)
AU  - U.S. Geological Survey
PY  - 1977
DO  - 10.3133/70203438
UR  - https://pubs.usgs.gov/publication/70203438
ID  - 70203438
ER  -