1. S. J. Dick, Plurality of worlds: the origins of the extraterrestrial life debate from Democritus to Kant., Cambridge University Press, Cambridge, 1984.
2. S. J. Dick, Life on other worlds. The 20th-century extraterrestrial life debate., Cambridge University Press, Cambridge (UK), 1998.
3. S. J. Dick, The biological universe. The twentieth century extraterrestrial life debate and the limits of science., Cambridge University Press, Cambridge (UK), 2000.
4. S. A. Arrhenius and H. Borns, Worlds in the making; the evolution of the universe, Harper & brothers, New York and London, 1908.