I just published a long article, in French, about the links between country-rock and southern rock, in "Bands of Dixie" magazine. If you read French, I can send it to you.
In the next issue, I prepare another article intrducing some of the best country rock records of the seventies (Dillards&Clark, Poco, PPL Firefall...).
Yet I wonder if it has already been done in english in a magazine you may know?