Two Pins and a Length of String: Kepler's Vision

Kepler J 1596 Mysterium Cosmographicum in Astronomi Opera Omnia, edited by Christian Frisch (1858, Frankfurt am Main and Erlangen)

Kepler J 1619 De Harmonice Mundi English translation by Wallis C G 1939 The Harmonies of the World in Great Books of the Western World edited by Hutchins R M (Encyclopaedia Britannica) pp 1007–1085

Kepler J 1634 Somnium English translation by Rosen E 1967 Kepler's Somnium: The Dream, or Posthumous Work on Lunar Astronomy (Madison, Milwaukee and London: University of Wisconsin Press)

Armitage A 1966 John Kepler (London: Faber and Faber)

Caspar M 1950 Johannes Kepler (Stuttgart), English translation by Hellman C Doris 1959 (London and New York: Abelard-Schuman)

Koestler A 1959 The Sleepwalkers (London: Hutchinson)