No copyright notice ("Copyright by whomever" or
the "circled C" mark) is necessary to claim the
copyright for a work. All creative works, under US law, are
automatically copyrighted by their authors at the moment of
creation (unless done as a work for hire under contract).
So all of the questions in the Stanford archive are
indeed already copyrighted, by the question writers and
editors.
More information can be found at
www.loc.gov/copyright
Regards,
Joseph Gratz
U of Wisconsin College Bowl
(And a
theatrical sound designer all too familiar with copyright
and public domain)