Required:
Allan M. Winkler, The Politics of Propaganda: The Office of War Information, 1942-1945 (New Haven: Yale University Press, 1978), pp. 1-7, 149-57 (pdf).

Suggested:
M.A. Doherty, Nazi Wireless Propaganda: Lord Haw-Haw and British Public Opinion in the Second World War (Edinburgh: Edinburgh University Press, 2000).

John Carver Edwards, Berlin Calling: American Broadcasters in Service to the Third Reich (Westport, CT: Praeger, 1991).

Holly Cowan Shulman, The Voice of America: Propaganda and Democracy, 1941-1945 (Madison: University of Wisconsin Press, 1990).