„Orbits“. ESA. October 4, 2018. Nuoroda tikrinta October 1, 2019.
harvard.edu
ui.adsabs.harvard.edu
Wertz, James Richard; Larson, Wiley J. (1999). Larson, Wiley J.; Wertz, James R. (eds.). Space Mission Analysis and Design. Microcosm Press and Kluwer Academic Publishers. Bibcode:1999smad.book.....W. ISBN978-1-881883-10-4.