The n-body problem concerns the motion of n celestial bodies moving in space in accordance with Newton’s law of universal gravitation.Calculus of variations is perhaps the most popular methodology in finding solutions for the n-body problem in recent years,especially for solutions which exhibit plentiful symmetries.In [?] we construct a special class of solutions named retrograde orbits for the 3-body problem with various choices of masses,a result refined later in [?] but still confined to the case of three bodies when masses are non-equal.