Many Body Structure of Strongly Interacting Systems Refereed and selected contributions from the symposium “20 Years of Physics at the Mainz Microtron MAMI” - Arenhövel, Hartmuth; Backe, Hartmut; Drechsel, Dieter; Friedrich, Jörg; Kaiser, Karl-Heinz; Walcher, Thomas (Springer Berlin Heidelberg, 2006)