1. NASA, Solar System Exploration, Science & Technology. Web site http://solarsystem.nasa.gov/scitech/display.cfm?ST_ID=2548
2. NASA, Jet Propulsion Laboratory, Solar System Dynamics, Astrodynamic Constants. http://ssd.jpl.nasa.gov/?constants
3. NASA, Planetary Fact Sheet—Metric. web site http://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html
4. NASA/JPL. web site http://www2.jpl.nasa.gov/basics/bsf4-1.php
5. Curtis, H.D., Orbital Mechanics for Engineering Students (Butterworth-Heinemann, Oxford, 2005) ISBN 0-7506-6169-0