On Peres approach to Fradkin-Bacry-Ruegg-Souriau's perihelion vector
  We solve explicitely the differential system obtained by Peres for the construction of a conserved vector associated to any central potential. We then obtain a very direct access to the discontinuous behavior of this Fradkin-Bacry-Ruegg-Souriau perihelion vector. 
Yves Grandati (FCN, LPMC - Ea 3468), Alain Berard (FCN, LPMC - Ea   3468), Herve Mohrbach (FCN, LPMC - Ea 3468)