Two inspiration sources appear clearly: contemporary American gangster movies and Alfred Döblin’s novel Berlin Alexanderplatz (1929). Two inspiration sources appear clearly: contemporary American gangster movies and Alfred Döblin’s novel Berlin Alexanderplatz (1929). Two inspiration sources appear clearly: contemporary American gangster movies and Alfred Döblin’s novel Berlin Alexanderplatz (1929). Two inspiration sources appear clearly: contemporary American gangster movies and Alfred Döblin’s novel Berlin Alexanderplatz (1929).