http://7lvwsn4fohcnaw5ije6j52aurmwaovqdzj4drfrj5aqget3nwwneshid.onion/wiki/United_States_Geological_Survey?lang=en
Retrieved June 17, 2010 . ^ "US Topo Product Standard" . www.usgs.gov . U.S. Geological Survey. February 13, 2019 . Retrieved April 29, 2025 . ^ Davis, Larry R.; Fishburn, Kristin A.; Lestinsky, Helmut; Moore, Laurence R.; Walter, Jennifer L. (2019).