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
Article, 1961, Roland F. Pease Jr. Testimonial of Roland F. Pease Jr. on the blue monochromes seen at the Leo Castelli exhibition, 1961