r├ętrograde

[1984] On the Retrograding of Planets ; N. M. Swerdlow ; Journal for the History of Astronomy 15 (1984) p. 30 [lien]
[1998] An Analysis of Ptolemy's Treatment of Retrograde Motion ; D. MacMinn ; Journal for the History of Astronomy 29 (1998) p. 257 [lien]
[2005] Using retrograde motion to understand and determine orbital parameters ; Bruce G. Thompson ; American Journal of Physics 73 (nov 2005) p. 1023 [lien]