John Witherspoon, "Introductory Lectures on Divinity," in The Works of the Reverend John Witherspoon, vol. IV (second edition, Philadelphia: William Woodward, 1804), p. 20
Brynjolfsson, Eric,McAfee, Andrew(2014).The Second Machine Age: Work, Progress and Prosperity in a Time of Brilliant Technologies.New York:W. W. Norton.