1. On the function and the probable origin of Ptolemy’s equant
2. The Empirical Foundations of Ptolemy's Planetary Theory
3. Evans James, The history and practice of ancient astronomy (New York, 1998), 364.
4. The details of the calculation may be found in Pedersen Olaf, A survey of the Almagest (Odense, 1974), 285–6, or Neugebauer Otto, A history of ancient mathematical astronomy (New York, 1975), 179–80.