Freeman J. Dyson (3 August 2004). Infinite in All Directions: Gifford Lectures Given at Aberdeen, Scotland April--November 1985. HarperCollins. p. 5. ISBN 978-0-06-072889-2; pbk edition with a new introduction by the author{{cite book}}: CS1 maint: postscript (link) 978-0-06-072889-2