↑Ohio Historical Society (2005). "Superman". Ohio History Central: An Online Encyclopedia of Ohio. Ohio Historical Society. Nakuha noong 2007-01-30. In the early twenty-first century, Superman remains one of the most popular comic book characters of all time. He also has been an immense draw in movies and on television.
↑Holt, Douglas B. (2004). How Brands Become Icons: The Principles of Cultural Branding. Boston: Harvard Business School Press. pa. 1. ISBN1-57851-774-5.
↑Koehler, Derek J.; Harvey, Nigel (2004). Blackwell Handbook of Judgment and Decision Making. Blackwell. pa. 519. ISBN1-4051-0746-4.
↑Dinerstein, Joel (2003). Swinging the machine: Modernity, technology, and African American culture between the wars. University of Massachusetts Press. pa. 81. ISBN1-55849-383-2.