I don't know if you've read 'The Mysterious Stranger and the Critics,' edited by Tuckey, or not - well worth reading, even if much of it is excerpts from longer works. Hamlin Hill's biography of Twain ('MT, God's Fool') covers the last ten years of his life and is an excellent read for background. I'm currently working on a paper on The Mysterious Stranger manuscripts which may lead into a bachelor's thesis on Twain's later period myself - score one for synchronicity Bill Kte'pi