0.28 John Solomon Otto Augustus M. Burns, The Use of Race and Hillbilly Recordings as Sources for Historical Research: The Problem of Color Hierarchy among Afro-Americans in the Early Twentieth Century, The Journal of American Folklore, 1972.

{ black african negro white } 0.28
{ song music musical folk } 0.15
{ doe make world point } 0.10
{ form number part found } 0.09