Flushing, New York, 23 May 1939 - Institutional correspondence Simon Guggenheim's and Dana C. Backus's form letter to ask for donations
Amsterdam and Brussels, 1956 - Exhibition catalogue Guernica: avec 60 études et variantesGuernica: met 60 studies et varianten
1956 - Conferences and articles Text by Emil Langui for the exhibition catalogue Guernica, avec 60 études
Brussels, 19 July 1957 - Institutional correspondence A letter from Émile Langui to Pablo Picasso, 19 July 1957
Brussels, 19 July 1957 - Institutional correspondence Émile Langui's letter to Pablo Picasso, dated 19 July 1957
Brussels, 6 September 1957 - Institutional correspondence Émile Langui's letter to Pablo Picasso, dated 6 September 1957