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M.Grant Gross, Oceanography, second edition, Charles E. Merrill Publishing Co., p.114, 1971, Columbus, Ohio.
UK Tidal Predictions Archived 2005-04-06 at the Wayback Machine http://www.pol.ac.uk/ntslf/tidalp.html
NOAA Tides & Currents http://tidesandcurrents.noaa.gov/tide_predictions.shtml