I have long been curious to know what primary documents,
letters, photos, etc. might be available to Twain researchers
at the Mark Twain Museum in Hannibal.  It's possible
that an actual inventory of such items does not exist?
Or is it not made public?

On the other hand, the Birthplace at Florida, which
inherited the holdings of The Mark Twain Research
Foundation (once headed by Chester Davis) has provided
an extensive list of those items which include a number
of interesting primary resources -- among them a number
of letters from Twain's acquaintances to Albert Bigelow