Helmut Friedel, Tina Dickey, Hans Hofmann, Städtische Galerie im Lenbachhaus München (1998). “Hans Hofmann: Wunder Des Rhythmus und Schönheit Des Raumes : [exhibition at the Städtische Galerie Im Lenbachaus in Munich, from 23 April to 29 June 1997, Schirn Kunsthalle, Frankfurt, from 12 September to 2 November 1997 ]”, p.95, Hudson Hills
Stafford Cripps's Speech in the House of Commons opposing the National Government's decision to expand the Royal Air Force, api.parliament.uk. July 30, 1934.
"A method for finding curved lines enjoying properties of maximum or minimum, or solution of isoperimetric problems in the broadest accepted sense". Book by Leonhard Euler, 1744.
"Neil deGrasse Tyson and Executive Producer Ann Druyan Talk COSMOS: A SPACETIME ODYSSEY, Public Appetite for Science, and More". Interview with Christina Radish, collider.com. March 17, 2014.