Clayton Cox died in 1995; I am not sure if copies of "Appalachian Crossroads" are still available. Clayton also published the periodical, "The East Kentuckian" for several years. I believe it was purchased and is still in publication, therefore, someone must know if any of his materials are still available. I will let you know if I hear.
The library of Congress Cat. Card number is 77-74669, so must be on file there.
The books were published by; Gateway Press, 1001 N. Calvert Street, Baltimore, MD 21202; They might know.
Wish I could be of more help.