The original Froissart–Stora equation was derived for polarized protons. It may also be applied to polarized electrons in storage rings. In this case, there are additional polarization effects resulting from the synchrotron radiation. In particular, the Sokolov–Ternov effect describes the polarization due to spin flip radiation. In the case of a non-planar ring, this must be generalized as was done by Derbenev and Kondratenko.