Cladders, J. Robert Indiana: Number paintings, 1966?
De Maria, N. EE AA stop campane, c1983 p. 5 (Museum Haus Lange in Krefeld) colophon (Kunstmuseum der Stadt Krefeld)
Der Deut. Museumführer, c1983 (article on Krefeld: Museum Haus Lange)
Ein Ort für Kunst, cl995 t.p. (Haus Lange) p. 13 (Museum Haus Lange) p. 11 (designed by L. Mies van der Rohe, built 1928-29 as private residence for H. Lange, given to the city of Krefeld in 1966)