I've just found that Archie Green's seminal article, "Hillybilly Music: Source and Symbol" (referred to by Stewie, above) is available online within the UNC Southern Folklife Collection's online exhibit of the same name:

Hillbilly Music: Source and Symbol is a virtual exhibit space of the Southern Folklife Collection at the University of North Carolina at Chapel Hill. It draws on images, songs, and texts presented during the April 2003 conference entitled Hillbilly Music Sources and Symbols: Country Music, Cultural Brokerage and O Brother, Where Art Thou? The original exhibit celebrated the publication of Country Music Sources (SFC/JEMF, 2002) by Guthrie T. Meade Jr., Dick Spottswood and Douglas S. Meade.

I've not explored the whole site yet, but it looks like an outstanding resource.

~ Becky in Long Beach