New York, 30 August 1979 - Institutional correspondence A letter from Ethen Shein to Richard E. Oldenburg
New York, 8 May 1968 - Institutional correspondence Antonio Serrano's letter to Fernando María Castiella
May - July 1992 - Institutional correspondence Loaned works at the Museo Nacional Centro de Arte Reina Sofía in conjunction with the rearrangement of holdings between the Reina Sofía and Museo Nacional del Prado