Wong Chia-ho . WHY CAN THE MAJOR PLANETS HAVE THEIR SATELLITES MOVING IN DIRECT AND RETROGRADE ORBITS AS WELL?. Applied Mathematics and Mechanics (English Edition), 1991, 12(4): 339-343.
[1] Wong Chia-ho,Why we have not yet found a retrograde planet in the solar system Appl.Math.and Mech.,11,5(1990),421-428. [2] Smart,W.M.,Celestial Mechanics(1953),21. [3] Encyclopedia,China(1980),529.(in Chinese). [4] Ehricke,Krafft A.,Space Flight,1(1960),124.