 Complete the following phrase:  At the end of World War II he formed part of a Dresden artistic group known as Künstlergruppe der ruf - befreite Kunst Call to an art in freedom along with Karl von Appen, Helmut Schmidt-Kirstein and Christoph Hans, among others. In this city he made an experimental report named Dresdner Totentanz Dance of death in Dresden as a condemnation of the 