Frankly, this is one of those questions that looks straightforward
but obscures so much; the process of gathering info on Micheaux has been
slow but steady, and earlier sources are now corrected by more recent
discoveries.  Anyway, start with the books by Thomas Cripps (BLACK FILM AS
GENRE, SLOW FADE TO BLACK), and move on to Manthia Diawara's anthology
BLACK AMERICAN CINEMA (essays by Cripps, Jane Gaines, and Ron Green), but
perhaps most importantly contact and support the Oscar Micheaux newsletter
published at Duke by Jane Gaines and Charlene Register.  The latest issue
has a list of the availabile films by Micheaux on 35mm, 16mm, and video
which I put together.  It also has a review of a recent documentary on
Micheaux and regularly reports on early black film.