The Everly Brothers: Harmonies From Heaven(2016)

Overview:

Documentary which celebrates, over the period covering the end of the 1950s and the beginning of the 60s, the phenomenon of the Everly Brothers, arguably the greatest harmony duo the world has witnessed, who directly influenced the greatest and most successful bands of the 60s and 70s - The Beatles, The Stones, The Beach Boys and Simon & Garfunkel to name but a few.