One of the interesting things about the Los Angeles punk scene was how many of its bands drew significantly on country music in putting together their sound. This was true of groups like the Gun Club, Wall of Voodoo, and — especially — X. It wasn’t just the retro twang of Billy Zoom’s explicitly rockabilly-based guitar style; it was also John Doe’s rich baritone voice and the open, modal harmonies that he and singer Exene Cervenka utilized. On Under the Big Black Sun, the band’s third album, you hear that influence fully integrated into their sound on songs like “Riding with Mary” and the brilliant “Blue Spark” — not to mention their take on the 1930’s pop song “Dancing with Tears in My Eyes.” X’s first three albums are all essential, but this one is first among equals.