Buying a book?

You want guitar transcriptions (tablature) for most of his recordings? Go here:

http://www.sheetmusicplus.com/store/smp_detail.html?item=3609444&cart=34255557621397118&cm_re=289.1.4-_-Results+Item-_-Title

Piano style arrangements (melody line, chords, etc.,), of all his recorded work? Go here:

http://www.sheetmusicplus.com/store/smp_detail.html?item=4993928&cart=34255557621397118&cm_re=289.1.4-_-Results+Item-_-Title

None of these books were written by Johnson, obviously. But the author of the first book, Woody Mann, is a well-known writer and teacher specializing in bottle neck slide guitar, among other things.

You'll also see, if you look around this music book store site, many other Robert Johnson books, so you can get other ideas as well.

Hope this helps.

Peace