I have recently published The Yale Book of Quotations (Yale University
Press), intended to be a much more comprehensive (particularly for modern
and American quotations) and thoroughly researched quotation dictionary
than Bartlett's or Oxford.  There is a large section of 153 quotations
under Mark Twain, the largest section for anyone other than Shakespeare
and the Bible.  For a number of the quotations, particularly those of
dubious authenticity, I give better evidence than has ever before been
brought forward for their earliest usage.

I would welcome suggestions from Twainists of additional quotations or
additional information about quotations already included, for possible use
in the next edition of The Yale Book of Quotations.

Fred Shapiro
Yale Law School