Krugman, Paul (14 October 2003). "Don't Look Down". The New York Times. Retrieved November 25, 2019.
remarque.org
O'Donnell's Laws of Cartoon Motion", Esquire, 6/80, reprinted in IEEE Institute, 10/94; V.18 #7 p.12. Copy on WebArchived 2012-03-14 at the Wayback Machine
O'Donnell's Laws of Cartoon Motion", Esquire, 6/80, reprinted in IEEE Institute, 10/94; V.18 #7 p.12. Copy on WebArchived 2012-03-14 at the Wayback Machine