Country Music: The Masters (Sourcebooks, $49.99) is a love song by Marty Stuart, the great country singer, to the extraordinary figures that make, and have made, country music America’s music. From the moving final portrait of Johnny Cash to photographs of Little Jimmie Dickens and Merle Haggard, you have an invaluable document. There are pictures of Elvis Presley’s guitar and of Minnie Pearl’s hat; you can see the handwritten lyrics of Loretta Lynn’s “Coal Miner’s Daughter.”  Everywhere you look there is something that adds to your knowledge of the history of country music and its contributors. Also included are a CD containing 21 songs and a DVD of a music video of Stuart’s “Dark Bird.”