NativeGround.com has reprinted a very good overview of the Delmore Brothers written by John Lilly for the Old Time Herald:

http://www.nativeground.com/delmorebrothers.asp

The two excellent overviews of the Delmores that County Records put together (Brown’s Ferry Blues and Sand Mountain Blues) are now out of print and command obscene prices. You can, however, pick up a very good box set from JSP called Classic Cuts for less than thirty bucks.