The internet is the world's greatest library but sometimes it's too scattered. I used many online sources in my research and have listed some underneath. Have a browse. There is nothing better than going down a Johnny Cash rabbit-hole.

Johnny Cash and Kingsland - Forbes Magazine

Johnny Cash information site

Official Johnny Cash site

BBC Johnny Cash page

Legacy site

Frank Skinner's tribute to Johnny Cash

Johnny sings with his mother, courtesy of Rolling Stone Magazine

John Carter Cash discusses the tribute album to Johnny Cash