"Parerga and Paralipomena: Short Philosophical Essays, Volume 1 (Sketch of a History of the Doctrine of the Ideal and the Real)". Book by Arthur Schopenhauer translated by E. Payne, 1974.
Robert Storr, Gerhard Richter, Museum of Modern Art (New York, N.Y.) (2002). “Gerhard Richter: Forty Years of Painting”, p.67, The Museum of Modern Art