(1984). Geological Survey Research, Fiscal Year 1981: A summary of recent significant scientific and economic results accompanied by a list of geologic, hydrologic, and cartographic investigations in progress. U.S. Government Printing Office.
Chicago-Zitierstil (17. Ausg.)Geological Survey Research, Fiscal Year 1981: A Summary of Recent Significant Scientific and Economic Results Accompanied by a List of Geologic, Hydrologic, and Cartographic Investigations in Progress. Washington: U.S. Government Printing Office, 1984.
MLA-Zitierstil (9. Ausg.)Geological Survey Research, Fiscal Year 1981: A Summary of Recent Significant Scientific and Economic Results Accompanied by a List of Geologic, Hydrologic, and Cartographic Investigations in Progress. U.S. Government Printing Office, 1984.