Article, 1961, Roland F. Pease Jr. Testimonial of Roland F. Pease Jr. on the blue monochromes seen at the Leo Castelli exhibition, 1961
Document, 1964 Invitation card for the exhibition "Yves Klein Peintures de feu" at the Galerie Schmela, Düsseldorf
Photo, 1959 Inauguration of the Gelsenkirchen Opera Theater in the presence of Jean Tinguely and Yves Klein
Photo, 1959 International collaboration between artists and architects in the realisation of the new Gelsenkirchen Opera House