New York, 3 September 1981 - Internal institutional documents Inventory and conservation report on the works collected by New York's Museum of Modern Art to be sent to Spain
Farmington, Connecticut, 20 September 1946 - Personal correspondence James Thrall Soby's letter to William Lieberman
New York, 8 September 1981 - Internal institutional documents A confidential and private document signed by Álvaro Martínez-Novillo and José María Cabrera in New York