To my (shallow) ear, the John Koerner (as well as Glover and Ray) of the 60's is almost sui generis. I can think of no blues style that came before him like his and yet he sounds like part of the rural acoustic blues tradition. As such, it would be wonderful to either have a book of some of his music, an instructional video, or both. I think he is an underappreciated resource.
Happy, what do you think?