Photo, janvier 1961 Yves Klein next to a Sponge Relief (RE 10) lors de son exposition "Yves Klein Monochrome und Feuer", Museum Haus Lange
Article, 1961, Roland F. Pease Jr. Testimonial of Roland F. Pease Jr. on the blue monochromes seen at the Leo Castelli exhibition, 1961
Photo, 1959 International collaboration between artists and architects in the realisation of the new Gelsenkirchen Opera House