Try "Was Huck Black?" (or similar title, I don't exactly recall) by Shelly
Fisher-Fishkin, one of her recent essays on Twain.  And there are a number
of books on why HF was banned (for its "bad grammar", not its "racist"
quality, as once put forth on this list) and subsequent essays.  There's
also a book of a collection of essays on HF that includes a chapter that is
a transcript of a _Nightline_ broadcast concerning HF's banning.  It's
interesting reading.  I'll try to conjure up the name.......Enjoy HF!  Beth