``Charge-Dyon" System As The Reduced Oscillator
  It is shown, that in the general case the Kustaanheimo-Stiefel transformation (reduction of $4d$ oscillator on the twistor space by the Hamiltonian action of $U(1)$ with further time-reparametrization) leads to the integrable system, describing the interaction of a spinless electrically charged particle with a dyon . 
A. Nersessian and V. Ter-Antonian