1972. 2012-11-16T19:53:21Z. 2023-02-09T21:27:15Z. Hansen, Robert E. Dept. of the Interior, U.S. Geological Survey. English. Public. Iowa.
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1978. 2014-02-28T20:15:38Z. 2014-03-13T22:16:13Z. Hansen, Robert E. Dept. of the Interior, U.S. Geological Survey. English. Public. Iowa and U.S.
1975. 2013-08-30T16:36:12Z. 2013-09-04T19:53:07Z. Hansen, Robert E. Dept. of the Interior, U.S. Geological Survey. English. Public. Iowa and U.S.
1973. 2013-04-23T19:50:07Z. 2023-02-09T21:27:16Z. Hansen, Robert E. Dept. of the Interior, U.S. Geological Survey. English. Public. Iowa.