There is a wonderful recent collection by the contemporary Fisk Jubilee
singers available.
Also, if you have some interest in these 19-th century genres, you might
like to get the 4-cd collection "Wade in the Waters," which has some nice
spirituals and so forth.
A great book that I would recommend is by my colleague and friend at
Michigan State, David Stowe: HOW SWEET THE SOUND. It also comes with a cd,
that provides much of the music discussed in the book.
Harold K. Bush, Ph.D
Saint Louis University
St. Louis, MO