His works are exhibited throughout the world .
His works are are represented in all the most important German collections , et al. at the Kunsthall Hamburg , the Museum Ludwig in Cologne , the Nationalgalerie Berlin , and the Museum of Modern Art .
His works are exhibited throughout the world and are represented in all the most important German collections , et al. at the Kunsthall Hamburg , the Museum Ludwig in Cologne , the Nationalgalerie Berlin , and the Museum of Modern Art .