Bäcklund transformations in general relativity -- Prolongation structures and differential forms -- Vector backlund transformations and associated superposition principle -- HKX-transformations an introduction -- HKK transfornatlons: Some results -- The Geroch group is a Banach Lie Group -- On the homogeneous Hilbert problem for effecting Kinnersley-Chitre transformations -- The homogeneous Hilbert problem: Practical application -- Noniterative method for constructing exact solutions of Einstein equations -- Inverse scattering, differential geometry Einstein-Maxwell solitons and one Soliton Bäcklund transformations -- Classical aspects of Yang-Mills theories -- Exact solutions of ?Pn models -- Explicit and hidden symmetries of dimensionally reduced (super-) gravity theories -- N-Kerr particles -- Algebraically special shearfree, diverging, and twisting vacuum and Einstein-Maxwell fields -- Exact solutions in cosmology -- The Newtonian limit -- Projective relativity and exact solutions -- Exact Brans-Dicke-Bianchi solutions.