ISBN 0-7141-1746-3* Another demonstration of the complexity of observed orbits when assuming a geocentric model of the solar system* Geocentric Perspective animation of the Solar System in 150AD* Ptolemy’s system of astronomy* The Galileo Project – Ptolemaic System
== External links ==* Another demonstration of the complexity of observed orbits when assuming a geocentric model of the solar system* Geocentric Perspective animation of the Solar System in 150AD* Ptolemy’s system of astronomy* The Galileo Project – Ptolemaic System