Generalized Fokker-Planck equation: Derivation and exact solutions S. I. Denisov, W. Horsthemke and P. Hänggi Eur. Phys. J. B, 68 4 (2009) 567-575 Published online: 08 April 2009 DOI: 10.1140/epjb/e2009-00126-3