At the beginning of the war, the future did not look bright for the music publishing business. Following Pearl Harbor, sheet music sales went into a slump, but then staged a sharp comeback in the weeks after December 7, 1941. Especially profitable were sheet music sales of "The White Cliffs of Dover," "Elmer's Tune," and "Chattanooga Choo-Choo." The only war song with any noticeable sales listing in late January 1942 was "You're a Sap Mr. Jap"--advertised in Variety as "America's Greatest Novelty."
                --Katheleen E.R. Smith, God Bless America: Tin Pan Alley Goes to War (University Press of Kerntucky, 2003, p. 145)