Meudon, 19 November 1955 - Institutional correspondence Nelly Van Doesburg's letter to Louise Boyer, dated 19 November 1955
Zurich, 12 December 1955 - Institutional correspondence A letter from Klaus Herdeg to Willem Sandberg
Meudon, 19 November 1955 - Institutional correspondence Nelly Van Doesburg's letter to Louise Boyer, dated 19 November 1955
Meudon, 29 December 1955 - Institutional correspondence Nelly Van Doesburg's letter to Louise Boyer, dated 29 December 1955