A few months ago I saw a trade paperback about folk musicians and folk music. I browsed through it, found it to be heavily towards "popular" folk music. It also left out our gave short shrift to some seminal performers. The tome was part of a series, others being rock & roll and Jazz, I believe. It had a hefty cover price so I put it back.. Since I was not impressed with it, I do not remember the title...but I think it may have been a Rhino Records publication.