Registration sheets for the entry of Guernica and associated works at the Casón del Buen Retiro, sent by the Museum of Modern Art in New York. 

Reference in the source Archive:
Caja : 101 / Legajo: 16.05 / Nº Exp: 8 / Nº Doc: 5
Registration sheet for the Picasso works deposited at the Casón, including Guernica