Just a quick note to say that I have assigned _Mark Twain A to Z_ in Twain
seminars (juniors,Plan II honors program, University of Texas) for two
semesters, and the students have found it invaluable. The historical and
biographical background  enriches their understanding enormously. The plot
summaries don't deter them from reading the books; they do allow them to
refer to specific chapters more conveniently in our discussions, and they
help everyone literally be "on the same page" in class.