"The World as Will and Representation, Volume II (On the Vanity and Suffering of Life)". Book by Arthur Schopenhauer (1819), as translated by R. B. Haldane and J. Kemp in "The World as Will and Idea" (p. 389), 1886.
Ruhollah Khomeini's address to an audience of Iranian industry workers and inventors (October 1983), as quoted in "Imam's Sahife", Volume 18 (pp. 189-190), December 11, 1983.
Ken Blanchard (2009). “Leading at a Higher Level, Revised and Expanded Edition: Blanchard on Leadership and Creating High Performing Organizations”, p.13, FT Press