Quadratic integrals of motions for the systems of identical   particles-quantum case
  The quantum dynamical systems of identical particles admitting an additional integral quadratic in momenta are considered. It is found that an appropriate ordering procedure exists which allows to convert the classical integrals into their quantum counterparts. The relation to the separation of variables in Schroedinger equation is discussed. 
Y. Brihaye, C. Gonera, P. Kosinski, P.Maslanka, S. Giller