Before revision: <ref> Michael Hardt and Antonio Negri, Multitude: War and Democracy in the Age of Empire (London: Penguin Books, 2004); Michel Foucault, The History of Sexuality (New York: Vintage Books, 1980).
After revision: Michael Hardt and Antonio Negri, Multitude: War and Democracy in the Age of Empire (London: Penguin Books, 2004); Michel Foucault, The History of Sexuality (New York: Vintage Books, 1980).