U.S. Geological Survey Data Series 170
By Douglas B. Stoeser, Nancy Shock, Gregory N. Green, Gayle M. Dumonceaux, and William D. Heran

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Version History
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Version 1.0: Posted February 2006

Version 1.1: Posted January 2007, the maps constructed from the databases in version 1.0 are now included as pdfs in version 1.1.