Rujukan Orbit

  1. ↑ Encyclopaedia Britannica. 2. 1968. m/s. 645.  Missing or empty |title= (bantuan)
  2. ↑ M Caspar, Kepler (1959, Abelard-Schuman), at pp.131–140; A Koyré, The Astronomical Revolution: Copernicus, Kepler, Borelli (1973, Methuen), at pp.277–279.
  3. ↑ Kuhn, The Copernican Revolution, pp 238, 246–252