Teen idol, rock pioneer, smooth crooner—here you can delve into all the Ricky Nelsons. Compare his train songs for a start—1967's “Mystery Train” chugs along like a Sun Studios rocker; 1971's “This Train” feeds glam-ish guitars into the engine. Nelson rocked, but was also a fine country singer, whether it was a touching ballad with sobbing slide guitar (“You Just Can't Quit”) or cantering country-rock with sighing pedal steel (“California”).