For anyone who has Netflix: there's a documentary on the legendary blues guitarist Robert Johnson right now. It's a great introduction to Johnson. Most of what we've been able to find out about his early life is explored, and the cultural background and roots of the infamous crossroads legend is discussed. His legacy is talked about in great detail, too. I wish it had told more about the background of the recordings he made in San Antonio and Dallas, but all in all this is a documentary I recommend.
Btw: Johnson's 94 year old stepsister Annye Anderson released a memoir this year, revealing the third known photograph of Robert in existence.
