References for Planetary motion
- Isaac Newton: The Mathematical Principles of Natural Philosophy, London 1687.
- Nicolaus Copernicus: On the Revolutions of the Heavenly Spheres, Nürnberg 1543.
- The laws appeared in Johannes Kepler (1571-1630): New Astronomy, Heidelberg 1609. They were validated in his later work: Epitome of Copernican Astronomy, Book V, Frankfurt 1621.
- A E L Davis: 'Some plane geometry from a cone ... 'Mathematical Gazette, forthcoming, July 2007.
- I. Bernard Cohen: The Birth of a New Physics, Norton 1985 (up-dated), p.166.
- Johannes Kepler: The Harmony of the World, Linz 1619. Stated Book V, Ch.3, Prop.8.
- A E L Davis: 'Kepler's potential proof of his Third Law' in Miscellanea Kepleriana, ed. Boockman, Di Liscia, Kothmann, Augsburg 2005.