Frank Sinatra had yet to escape the artistic shadow of Bing Crosby when he sang Crosby's self-mocking "Learn to Croon" as part of a 1940 Dorsey-band broadcast medley. (As for Our Gang's Alfalfa, who also essayed the tune, he never did escape.) Learn to Croon collects more Dorsey-Sinatra performances from the trove that produced its companion volume, It's All So New! Unburdened by that CD's load of amateur-song-contest submissions, Croon focuses instead...