Zurich, 12 December 1955 - Institutional correspondence A letter from Klaus Herdeg to Willem Sandberg
New York, 16 September 1957 - Institutional correspondence A letter from Monroe Wheeler to Katharine Kuh
London, 2010 - Exhibition catalogue Installation catalogue The Nature of the Beast, Whitechapel Art Gallery
New York, 6 September 1966 - Institutional correspondence Monroe Wheeler's letter to Alfred H. Barr Jr.
Whitechapel Gallery, London, April 5, 2009 – April 18, 2010 - Exhibition Installation The Nature of the Beast, Whitechapel Art Gallery
New York, 6 December 1957 - Institutional correspondence Monroe Wheeler's letter to Dorothy Miller and Alfred H. Barr Jr.