The link is to the university press catalogue, Al. I clinked on folksong/folk music and the first title I see is "Blues Mandolin Man: The Life and Music of Yank Rachell". Interesting as we don't often associate mandolin with blues.

Some other titles include "Ragged but Right: Black Traveling Shows, 'Coon Songs', and the Dark Pathway to Blues and Jazz", "Roosevelt's Blues: African-American Blues and Gospel Songs on FDR", "Transatlantic Roots Music: Folk, Blues, and National Identities", "The High-Kilted Muse Peter Buchan and His Secret Songs of Silence" (once suppressed collection of bawdy songs), "The Norumbega Harmony: Historic and Contemporary Hymn Tunes and Anthems from the New England Singing School Tradition" (many are the sort of books though that are begging for inclusion of a CD)

Prices are very reasonable, but as I'm abroad I would have to pay $10 per book extra for postage. In the U.S., the price is $5 first book, $3 each additional book.