
Was the World Made for Man? (1903): also p. 106, What is man?: and other philosophical writings, Volume 19 of Works, 1993, Mark Twain, Paul Baender, University of California Press
Source: At Home: A Short History of Private Life
Was the World Made for Man? (1903): also p. 106, What is man?: and other philosophical writings, Volume 19 of Works, 1993, Mark Twain, Paul Baender, University of California Press
From 1980s onwards, Grunch of Giants (1983)
Source: 1940s - 1950s, Introduction to Operations Research (1957), p. vii
Session 735, Page 576
The “Unknown” Reality: Volume Two, (1979)
From Hawking's article A Brief History of Relativity http://www.time.com/time/magazine/article/0,9171,993018-6,00.html, in Time magazine (31 December 1999)