U.S. Geological Survey Professional Paper 1648
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Professional Paper PDF file (12.8 MB)
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PLEASE NOTE:
This PDF file contains a correction to a typographic error that is present in
the printed version of this report. Equation (3), which is located on the page
numbered "5", was missing a "plus sign" in the denominator in the printed
version. Equation (3) is this PDF file is correct.