Amsterdam, 25 January 1956 - Transport documents M. Winter's letter to Robert Giron, dated 25 January 1956
Amsterdam, 25 January 1956 - Institutional correspondence M. Winter's letter to Robert Giron, dated 25 January 1956
Gerti Fietzek (ed.), Cologne: Buchhandlung Walther König, 2009 - Essay Maria Eichhorn. The Artist's Contract