An allusion is an element in a work that alludes to another piece of art, whether it be a book, painting, music, etc. Once Upon a Time in America contains many such allusions and I've tried to catalogue them on a webpage. Most obviously there are references to Hollywood gangster movies but I also discuss the Song of Songs, Martin Eden by Jack London, and Degas's paintings of dancers. I've had this page going for a while but I've recently greatly expanded the section on gangster movies. The page is here:
http://onceuponatimeinamerica.net/allusions.htmlHope you enjoy! If anyone has any other suggestions for the page please discuss here.
thanks,
Simon