When using the tide gauge data set from the PSMSL, we ask that you reference
the last paper describing the data set, as well as the data set itself.  As an
example, "the tide gauge data [Woodworth and Player, 2003; PSMSL, 2012] show
that ..."

Permanent Service for Mean Sea Level (PSMSL), 2012, "Tide Gauge Data", 
Retrieved 25 Jan 2012 from http://www.psmsl.org/data/obtaining/. 

Woodworth, P.L. and R. Player, 2003. The Permanent Service for Mean Sea 
Level: an update to the 21st century. Journal of Coastal Research,
19, 287-295.

Note above that the "Retrieved" date above should correspond to the "Extracted
from Database" date on the data page.  This date and advice is also
distributed in the zip files that contain the whole data set.  While
bibliographic requirements will vary from journal to journal, we believe that
is important to include the "Extracted from Database" date.