I'm surprised nobody has qualified their answers on the "five must read"
books about Mark Twain. Or maybe they have and I missed it.

Biographies? Bibliography? Criticism? It all depends...

If you go to www.abaa.org and click on "collector's corner" and then scroll
down the list of articles you will find my Twain articles from a 1998 Firsts
Magazine where I suggest a "Mark Twain Reference Shelf" and provide a brief
paragraph or two about each selection (Gee, I hope I gave the correct
directions for finding this...) I divided my selections into general
reference (MT A-Z and MT Encyc), descriptive bibliographies (Johnson and
BAL), other bibs (Tenney's guide, Budd on interviews, Fatout on speeches),
library and bookseller catalogues, biography (Paine, J Kaplan, Hill),
critical studies (Brooks and DeVoto), and miscellaneous reference works
(Berkeley edition, Gale on characters, Gribben on MT's reading, Machlis on
letters to/from, and the Twain's World CD for ferreting out themes and
topics by keywords).

Other than tooting my own horn,  I'm suggesting this approach because my
list of suggested works is short enough not be overwhelming, grouped by
genre, and lightly annotated, so anyone can use it in pretty short order to
make their own informed choices.

Kevin Mac Donnell
Austin TX